Dude, that is soooooooooooooooooo true. i've been playing at pokerroom for over a year now, and some of my worst beats have come from terrible players.
One example... 2/4 ring game... I get dealt wired bullets, raise to 4, 3 peeps call. flop comes up A 3 5 different suites. I bet, dude raises me, i re-raise, he caps. At this point I know something is up. I call his remaining bets, he shows 2 4 off-suite, for the wheel. I coulda ripped my f#%@!&g hair out. Guy wasn't even paying a small or big blind, and he stays into a pre-flop raise with deuce-four off-suite? Talk about crazy...