That is not, basically so do the players of two types, the first, who have a combination on the flop, but the further draw can significantly reduce the strength of their hands and the second,which is to take away the Bank immediately(basically they also have something on their hands) and force You,if you decide to call,play no chance!
Pay more attention to how these players are playing. It's a well known move to induce a call through a polarizing bet. Yes.. sometimes they will be bluffing. But ultimately you have to consider what hands would have made it in on the flop and what hands are sticking around (and why). Small stakes are notorious for players going with any two for pocket change. You absolutely need to know your opponents to have a better chance of making the right decisions.
In general, more then pot sized bet signifies very strong hand or a bluff. Literally no middle ground! My advice would be to call with very very strong holdings. If you really sometimes feel like villain is bluffing, then call with hands that don't have blockers for their draws that would have missed.