Zoom plo50 QsQJ9 utg, flop tp paired bd, mwp turned into bluff

You are rarely ever bluffing here, so it's a good spot if you think CO is calling the flop with draws or just to float, a checkraise is going to have a high success rate because it looks so strong after CO has already called.

You might even get a solid CO to fold an 8 with no kicker (like if he has 8654).

You're risking $21 to win $25 so this needs a 50% success rate. Heads up I would never try this because your checkraising range is going to be a lot wider than trips therefore players can't fold aces in that spot, however multiway opponents will assume you have to be tighter with your range here.

I also wouldn't checkraise if the flop was wetter (with a flush draw showing) because then your range becomes wider (since players will try to buy the pot with strong draws).

You can only pull this off with the exact scenario that happened. All you need to do is have some read on CO that he would raise this flop with trips (and therefore make his calling range be JJ/J8 and straight draws).

Also you can't rule out having the best hand, MP might have 3 bet preflop with something like 4567ds and is just hoping for 2 folds on the flop.