In speed chess (especially bullet), are dirty tactics tolerated more? In bullet chess, well, it's frantic. And sometimes I find myself making dubious checks just to gain time. Or funny gambits. But it feels unbefitting of the royal game. 

Is bullet chess bad for the overall chess community's reputation?
In my opinion chess and bullet chess are a kind of sport or competition. Everything what happens on the board is legitimate, if it is according to the rules. There is no such thing as an evil or devious move. You may play risky, repeat moves or do moves for "psychological" reasons. If the opponent thinks there is something wrong with that she or he needs to show it by playing better. 

Sometimes player continue playing a drawn position, because their opponent runs out of time and they hope that the opponent will blunder. That is fine, since time is part of the game. Anand won a game against Gelfand in this way in last world championship