Opponent cold-calls then caps preflop

[Magikist]

This is not ALWAYS AA, KK, AK, but in my experience it's one of those a high majority of the time. The only times this has been something like 89s or JTs is from fishy players. Because MP looks like a TAG and because it was only 3-way back to him when he capped, this is probably AA a lot of the time.

Even if it's a good multiway hand, players usually give up on flops they miss. Unless you have a terrible image, if he's still playing back at you, the very worst he has is spades, so he's got a lot of outs against you.

If you know this player well and you're sure he's a reasonable TAG, I think you could find a fold unimproved on the turn.

If he's any kind of unknown, or your image is bad or something like that, then a call down could be justified.