What are some examples of Players hindering the fun of the game, for the DM or for the other Players?
To be fair, DMs can do a lot of these as well, and I'm sure there are worse things, but I've seen these:
Player picks a PC name that pulls everyone out of the game every time it comes up.
Player never, ever pays attention to anything but combat rolls.
Player decides to suicide a character and assumes everyone else (even the whole campaign) must die with it.
Player shows up in no shape to play - very drunk, falling asleep etc.
Player shows up unprepared to play - no dice, books, paper, pencils, etc.
Player insists on taking game materials home (char sheets, campaign notes, group treasure sheets), and forgets them.
Player flakes - shows up very late, leaves early, or doesn't show up at all (without any notice).
Player asks to reschedule whole sessions around their schedule... and then doesn't show up.
Player asks everyone to cancel a whole session to fit their schedule... and then calls up looking for something to do that day.
Player brings baggage to the table (esp. if it involves other players).
Player brings friends, children or SOs "just to hang out and watch."
Player insists on playing extremely evil/good PCs when everybody has agreed not to.
Player has 100% encyclopedic knowledge of their character, their weapons, feats, and spells, where it will be (build-wise) in ten levels, etc. ... and have no idea what is actually going on in the game.
Player is unwilling to learn the rules on how their character works.
Player rules lawyers, but only when it benefits them.
Player rules lawyers, but badly and wrongly.
Player buys the adventure you're using and read it.
Player buys/downloads the adventure you're using and shares it with the rest of the group.
Player is a salesman or business owner and can't "turn off" - is constantly trying to sell things to other players and the DM.
Player consistently cheats.
Player accuses everyone else of cheating all the time.
Player is not able to handle being kicked out of a group, so he convinces your landlord to let him into your house while you're away, "retrieves" his character sheet, and tears up your game notes... crippling the campaign for the remaining players.