Only encountered two passengers that truly annoyed me...

1) Trying to talk me with earphones on and eyes glued to the scenery outside. Keeps patting my shoulder to strike up conversation. Five minutes after I tell him I really have interest in talking (I was in a foul mood), he makes some new excuse why he wants to talk. This goes on for entire 4 hour flight. He was too "nice" for me to just chew him out, unfortunately.

2) Very very large woman next to me. Spilled some her food onto my tray. Then spilled her tea in my lap. "Oh my god, I am like soooo sorry!"