Do you guys ever fold one? I suspect you would, but try this situation I"ll just fabricate real quickly:

Hand: 10c 5h

Flop: 10s 5c Kh

And somebody bets really high. Should I suspect a set, higher 2 pair, or maybe just high pair? This sometimes really gets me.

i always see low 2 pair losing to a bigger pair cuz the board pairs u jus wanna bet big on the flop n dont really wanna get called. of course u gotta watch out for sets but in that situation u would kno if they have a TT or KK set cuz they would raise pf. u jus gotta look out the the 55 set but u all the 5s r out so its not THAT likely

depends on their raising pre flop.

if there is no betting and like a 2 or a 3 falls then u can suspect it maybe, but most likely they are betting high pair w/ low kicker, trying to get ppl out, or they are bluffing a mid-pair. i'd say 99% of the time with a flop with no flush, re-raise it a lot.