Vague Question, but a situation I find myself in frequently..

[AceofSpades]

What your opponent did is also a great tactic to pick off possible (missed) continuation bets.

Cold calling a weak bet on the flop. And then seeing what you do on the turn. Then betting river if you look weak, which also oddly enough can look like a slow play of the nuts.

When you check behind it telegraphs you really don't like your hand, and that you probably fold if he bets on river.

of course it's also the same way some ppl would play trips in this case.

I'm betting the turn here, since you didn't "sell" that you had a pair of kings on the flop and check/folding river if called.