Opponents either seldom bluff or bluff far too often. Their bluff frequency is almost always wrong. With a half pot bet, if your opponent is bluffing more than 33% of the time call or raise. If they bluff less than 33% then fold. Most small stakes players do not bluff often enough.
Folding is a skill in small stakes games. Most don't bluff enough to make calling profitable. That changes in higher stake games.
The Flop is are the least reliable indicators. Big bets on the Turn or River are far more reliable. Time to fold.
It's what I have said before. Poker is all about frequencies and ranges. Knowing how to accurately know your own frequencies is vital to winning.