[phish]

I know what you mean. But there are plenty of times (happens much more in stud than holdem) where I know i'm behind with great certainty, but i will still make the play because i know that putting in that extra bet is +ev if I can knock out the third player. But if i'm in a situation where i can perhaps knock out the third guy, and my equity for that street is close to 0, then it's a freeroll and a no-brainer.
Failure to make such plays is VERY costly in stud. It's not so bad in holdem, but this situation just so screams out for that raise that I see it as a major mistake.