Suppose you're playing in a tournament. For the purpose of filling up your scoresheet, is it improper etiquette to ask your opponent what his/her rating is before the game?
Yesterday, I played a tournament match, and at the table next to me the guy asked his opponent for his rating. “I don’t really know...” was the reply, “about 1580, I think. And yours?”
“Euhm... about 1400”, the guy mumbles in reply.
If you don’t want to give out your exact rating in reply or you don’t know it yourself, I would not ask the question to begin with. Furthermore, I thought the question was bad etiquette and would not really be happy with my opponent asking it.
Finally, where I live, most tournaments have lists of all participating players and their rating which you can look at. So start the game, and then after a couple of moves, when your opponent is thinking, you can always go check the list.
PS: I find that I play better when I don’t know my opponent's rating. Once I know his rating is a lot better, I get nervous and consider myself lost from the start. When I know his rating is much lower, I tend to play reckless and make mistakes.
I don't think this would be a breach in etiquette - but I think it is a somewhat dangerous thing to do for you. Chess is as much about mental fortitude as it is about "playing skill" and regardless what your opponents answer is - it can get into your head and affect your play.
If your opponent is a lot lower rated than you are, it tempts you to play these "Maybe he won't see it" moves, if he is higher rated, you might overestimate a bad sacrifice or a blunder he does.
Considering the mental effects of a move, before and during the game, may prove to you as useful as considering the positional effects.
It isn't a beach of etiquette and is quite common in tournaments. Many scoresheets have a place to write the opponent's rating, so a lot of players ask while filling it out at the beginning of the match.
There's no shame in being low-rated anyway. With the exception of top players, we're all novices compared to someone.
Some people are a bit self conscious if they are lower rated - better to look it up on the tournament list or ask a teammate.
That said, if it's a team game and I don't recognise the opponent or their name on the team sheet then I might ask - I do feel it is important to have a ballpark idea of your opponent's strength.
You could also try google if most of your opponents are >1800 FIDE