Betting the river OOP to fold a worse hand.

[slamhound]

This is a situation that I'm having trouble with. I'll end up on the river with a hand that has marginal showdown value (mostly A/K-high, occasionally small pairs and very occasionally stuff like Q-high), and I think could go either way slightly in terms of EV if I check/call and the villain were to bet every time.

When I have the lead, I don't bet blank rivers very often UI and I'm running into situations where I'm getting "floated" and getting bet into on the river with a mix of bluffs and made hands (the bad players are easy to pick off, the better ones aren't).

Do I need to bet more rivers UI? Am I missing something really basic here?