It sounds like you're a beginner. As such, you should be focusing more on tactics than openings.
First, just because they play a move that's not in your book, doesn't mean it's "wrong". It may be an older line that's not in modern opening books, or just not in the books you have.
That being said, to answer your question, it depends on the opening. In a ...
It looks like your position fell apart pretty early on, a symptom of poor opening theory. Your King and Queen were exposed to attack within the first few moves, and White ruthlessly exploited that opportunity.
The first move that Stockfish classifies as a blunder (yes, there's more than one) is 5. … h6?? where you attempt to directly attack the advancing ...
A healthy approach towards learning openings is to retain the key ideas involved, and not to necessarily memorise move by move unless it's an extremely precise sequence in a very theoretical line (as is often the relevant case at high level chess). It's a bit analogous to how one would learn physics, by understanding the principles, drawing connections ...
Your proposal is a plausible way to get to that position. I wouldn't call the Scandinavian "bad" just because it moves a piece twice. It's perfectly playable.
When the trap was played in the following game, it was the knight rather than the queen which moved twice.
[Site "Sao Paulo (Brazil)"]
[White "Nobrega Adaucto Da "]
[Black "Barata ...
I mean, this is the main line and for a reason.
But I would be very surprised if most people's repertoire ended here, this is where it begins. The line goes
6.Bb5+ c6 7.dxc6 bxc6
And now White has a number of options. In all of them White stays up a pawn however Black gets some counter play. (and there isn't a great line to give back that pawn for initiative,...
The pattern starting from Nxf7 does not correspond to any known (opening) trap. It's to be expected as this does not really qualify as a trap for the following reasons:
The path up to the critical position 10.Nxf7 has major flaws, e.g. white is hanging a full knight on move 7.Ng5 (7...Qxg5), so objectively, white is already lost before any trap setup is ...
I don't think that this is an easy win at all. In fact it is not clear who is the trapper and who is the "trappee". To close the trap, White has no need even to develop. He can simply play Kd2!! followed by Bg2. This refutes, for example, N6e7.
The only defence that I can see starts with 8..e4! 9.Qxe4+ Kd8! 10.fxg6 hxg6. Without analysing further ...
[fen "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1 "]
1. e4 b6 2. d4 Bb7 3. Bd3 f5 4. exf5 Bxg2 5. Qh5+ g6 6. fxg6 Nf6 7. gxh7+ Nxh5 8. Bg6++
One possible trap for black is in the Matinovsky gambit which starts with ... 3.f5.
Nothing is ever certain, but when you are in position that was played in thousand of high class games, any deviation is virtually always dubious move. On the other hand in position which was played in lets say just 10 high class games, novelty is still more probably to be dubious, but it is nowhere close to be certain. Also there can be more equally strong ...
In essence this is why databases are used. No book has room for such data.
Basically if someone leaves your preparation, you need to pause and ask "what is wrong with that move", or when studying lines ask yourself "what about x". Of course the more you know the less you have to think over the board -- so yes, study the refutations to inferior replies, etc....
I am asking because if I wanted to teach somebody openings, I should obviously just first teach them principles, but what about these opening traps?
Exactly. There are many opening traps and if you don't know them they are very easy to fall into. For instance it is easy for a beginner playing the Ruy Lopez to fall for a trap which is so old it is called the ...
There is a saying that "the best way to refute a gambit is to accept it", attributed to Steinitz. While sayings in chess often have exceptions, I think it does apply to this particular case. If you go by either the Stockfish evaluation (-0.8) or the results of games between highly rated players (67% win for black out of 12 games), the gambit is a mistake.
Is it best for me to stop and eat clock time figuring out why the wrong move is wrong?
No, you should learn before the match what the responses to deviations are. If you don't know why deviations are "wrong" and how to punish them, then you don't really know the opening.
The initial way you gave is the overwhelming favorite way to get to that in the Mega Database. Out of the 72 games, that move order occurred 59 times (three times, white played Nf3, and only after did Nc3 Qd8 get played).
The other 13 times, saw Nd5; Bc4 Nc6 as in the game below. That game was the only one that had an ECO code of B02 somehow, with the rest ...
Owen's Defense is a bit passive, but quite solid opening, so there aren't that many traps to watch out for.
Here is a primitive one:
[Title "Owen's Defense"]
1. e4 b6 2. Nf3 Bb7 3. Bc4?! Bxe4? (3... e6) 4. Bxf7+ Kxf7 5. Ng5+ Ke8 6. Nxe4
Black has lost their castling rights, so there must be some advantage for white.
3. Bc4 isn't ...
This is really a question for the engines, but it's hard to believe
that Black has enough compensation here for his creatively sacrificed
material. White could also return a fraction of the material with
10 Nxe5!? dxe4 11 Nxc6 Qd6 12 Nxe7+ Qxe7 13 d4
and be just up B+N for R; or return a bit more material in your main line with
12 Qh5 followed by 13 Nc6!? ...
In my first 10 years of playing chess I never studied openings. I studied middle game, positional play, and endings. Falling for traps is a great way to learn about them, very memorable. I did play through many master games and so had a feel of openings from that.
Against strong opposition I often ended up in cramped positions struggling for activity out ...
1.e4 d5 2.exd5 Qxd5 3.Nc3 Qd8
Above is a playable line of the Scandinavian defense. 3...Qa5 and maybe also 3...Qd6 are more popular, but Qd8 isn't horrible.
The tactical trick itself is more general. It can occur, for example, in the following gambit line:
1.e4 c6 2.d4 d5 3.Nc3 dxe4 4.f3 exf3 5.Nf3 Nf6 6.Bc4 Bg4
Because it is a game and a contest/struggle. The opponent makes moves that are good for him not the moves in the favorite line you memorized.
Stop figuring out why his move is 'wrong' and figure out what your best move and plan is and then do that. Chances are that his move is quite good even if not the theoretical best.
You do not keep making your ...
I'm an FM so I guess I'm experienced. For Black's POV, the 12...e6 variation you gave is the best way to play. It pretty much stops White's attack and Black's just up a piece. If he really wanted to Black could have also gone for 11...Ke8 followed by ...e6. In any case, playing with ...e6 is the way to go since it covers up all Black's weak light squares.
I believe you should go for 9.h4 in the main line:
1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 d5 5.exd5 Na5 6.Bb5+ c6 7.dxc6 bxc6 8.Bd3 Nd5 9.h4
White is trying to keep his pieces on active squares at all costs.
There is a lot of complexity here, e.g. in the line 9...h6 10.Qh5 Qf6 11.Nh7!? Rxh7 12.Bxh7 g6 (don't play 11.Nxf7 hoping for 11...Qxf7 ...
This is just a series of bad moves by black.
The video linked to by koedem says it's a new "trap," and quite frankly, it requires white to resign after dropping the queen to qualify as a trap. If white continues 8. Nxc7+, when the dust settles, white still has a slight advantage, having traded a queen for a rook, two pawns and a bishop. (In this ...
Stockfish 10+ (depth 20) disagrees with the other answer, because it thinks that White's opening here is sound and evaluates the final position as +1.4. I would be very interested to see anyone play as Black starting from that position and beat Stockfish 10+. If nobody can, how can one consider White to have played badly?
Study Opening principles. At least get the basic foundation (first 5 moves ) of common openings. The biggest problem with opening tricks is that if you know how to counter them, you will have a decisive advantage.
At the 1400 level, players will seldom do random gambits and openings. The most common you will see from white is Queen or King's gambit, evans ...
As a practical matter, if you're playing to win, and you encounter a gambit you haven't seen before, don't take the material. Play defensively. This will be sub-optimal by engine standards, but will usually lead to a position that is easier to play. This is particularly true in your case, where you expect to outplay your lower rated opponent given enough ...
I think you know that 12..e6 for Black avoids all trouble and thus he was never in trouble until the successive blunders. So your Bxf7 sac is completely dubious.
Your problem is back at move 3 when you played Qxd4 and lost time to Nc6. At this point Black is already doing well.
Based on your play you might consider 3.c3 offering the Smith-Morra Gambit....