[schubes]

I'm guessing if this player was a loose gambooling type you would have said so in your post. Most 'decent' players pat bluff much less than they should. Don't bother with the game theory calling frequency here, you'd do better to simply fold except under special conditions.

Have they been standing pat more often then seems plausible? Could they be raising with very weak pairs that would be in big trouble against a 3-bet? Are they getting frustrated (e.g. getting raised often and forced to fold)? Are they aggressive and tricky?

When I first glanced at your post I figured your opponent was defending in the BB, and you open raised and put in the cap. This is a more interesting situation because your opponent could be fed up with folding the blind and 3-bet as a resteal. When you cap they figure trying a pat bluff is better than folding. Be more inclined to call in a resteal situation like that, especially under the conditions above.