The calling station who checks the river after calling two streets is not giving up. He's hoping you check back. He still has his hand. He just doesn't want to bet it.

Why they do it

Calling stations are passive all the way through. They'll call every street but they won't lead. When they check the river it doesn't mean they missed - it means they're waiting to call one more time. Don't give them a free showdown.

The adjustment

Bet the river for value when you have anything decent. He's calling. The check is not a white flag - it's just him doing what he always does.

What it's worth

Checking back a value hand on the river against a calling station because the board looks scary is one of the most common leaks against this player type. This is real money you're leaving behind every session.