Watch for the guys who like to compliment your game at a critical point in the game. My theory is that they are trying to deflect your attention from something they're hoping you've missed.
I was talking to somebody rated much higher than me once. I was down a bishop with just a rook on an open file. They had an undeveloped bishop and undeveloped rook. I should have placed my rook on the back file to prevent their bishop from developing. They pointed it out to me, so it isnt always true if you are just having a friendly game.
Watch for the guys who like to compliment your game at a critical point in the game. My theory is that they are trying to deflect your attention from something they're hoping you've missed.