So i'm up against an unknown villain and i have encountered 3 villain types when faced with very small bets relative to the pot. one might see the same bet size on all three streets. minbets. 2bb bets. 

TYPE I (one): THE NIT, he is desperately trying to win ANYTHING from his super strong hand and will make very small bets to ensure he gets paid. I'm paying off these villain's too much when i don't know they are nits YET.

TYPE II (two): STRAIGHT FORWARD, FIT-OR-FOLD: sizing indicates his hand strength. These are often the opponents you can raise to get them off their marginal made hands. Do make your story credible as they are capable of calling light when the draws miss. when its unclear whether my hand is best: usually pocket pairs when the board remains low or paired, so you call down with 66/77/88 and get shown 77/88/99. 

TYPE III (three): RANDOM SPAZZ, NO IDEA, TOO LIGHT: They simply have no idea what they doing. Will be simply betting for no reason at all. i see some very light value betting? or they simply don't want to check nor know where the CHECK button is. They might underbet call with hands that don't fit the board at all or hands like AK/AQ/AJ that are being completely overplayed on very co-ordinated flops medium- to low rundowns. As soon as i know this i simply aim for value and don't try bluff them.

What other strategies have you come up with?