Unusual street captures... those keeper moments you get only when you are least expecting them!
Unique expressions/faces.
Crazy colors (I love toy cameras)!
Angles (when appropriate... it's hard to explain).
Off centered subject matter.

Bored of:
crap in the name of street photography (who cares about a dumpster in the alleyway anyway).
boring poses (once again, it's hard to explain)

Just want to make a note that, some people can make even the flowers and birds and those dumpsters look pretty cool somehow... I've seen them. So in general, I don't really think there's a rule to what is a turn on or what is a turn off... it's all contextual...