I can explain from experience...not that it happens all the time....but
When I lose a great hand after getting crap cards for so long....Lets say I have 3 of a kind off the flop...and the rest are "rags"....When a player hits some kind of miracle flush, miracle straight.....It REALLY gets me going....I can not say it is "tilt" for sure, but I definitely tend to play differently....or in a pissed off mood....I do not go absolute broke like a true tilt, but it definitely affects my playing personally...
It actually happened last night....Some moron got a flush on the river, and I lost a GREAT hand.....next hand....I have ANOTHER super hand...and the guy gets a straight from holding on to the river...it wasn't even open ended
Realllllllllllllllllllllly sets me in a bad mood