I am relatively new to this site and it's great for my game; instant access to players of a wide variety of skill levels and styles.  Unfortunately, two things really get my goat - one, when I play white and play a strong opening move, the other player often aborts the game (nearly 50% of the time).  The other problem for me is players disconnecting after I play a move that has put them in real trouble.  Obviously, resignation is the "gentleman"'s choice in that situation.  I find it disrespectful and irritating when players disconnect without having the decency to concede!  

Tell them to stop it

I wouldn't get too worked up about it.  It is really annoying but their isn't much to be done about it.  The nice thing is chess.com automatically tracks these people.  I know from reading threads on this site that they do punish repeat offenders.

Unfortunately, the world, not just this site, is full of people like that.  Losers with no class, no etiquette.  Chess is a gentleperson's game and they really shouldn't be on this site as they do not qualify by definition.  You cannot stop them from being rude, just make sure oyu do not fall to their level.

Another irritating rude thing, is when people playing in a tournament are losing, so they go on vacation for 3 months to make you wait.  And then take the maximum time to move after that.  There is evil in the world and it rears its ugly head in many forms.