I dont have a problem with people looking for their golf balls, but anymore than the alloted 5 minutes then they should let the group behind (usually me

, play though).
People that dont rake bunkers - this drives me insane.
People who dont replace divots - ffs you want to enjoy the course so help keep it in good condition.
People who done repair pitch marks - as above really.
Some of these things drive me crazy, to the point where I have been so fed up waiting on each tee, not to be let through, so I plant a drive over their heads - they soon get the message.
One last thing - juniors without any kinda clue as to what golf ettiquete is. Cant be arsed to shout fore, even though they have nearly kneecapped you.