I'll occasionally check behind on the turn against someone that will call my c-bets with a large range and fold the turn to a second barrel. I'll do it if I think they have a weak hand that won't call a turn bet so they hopefully bluff the river or will call a river bet when a blank hits.

I agree though that against an unkown, especially at $25NL, you should be betting all 3 streets for value almost all the time.