Let's look at a hand that could actually happen, with a little dead money in the pot, to see how big of an edge a 52/48 can really be. 5/10, $1k effective stacks. tagg/laggish regular opens to $40 in MP, you repop him on the button with 22 to $140. folds back to MP who pushes. You have played with him enough to know that he has AKo/AKs here every time (I know this is assuming a lot and we're never going to be 100% sure here, but against some players, this assumption really isn't that far off at all).
You said it right there. You're never going to be 100% sure. You might be "not far off" but this is a really bad place to be any off. So as you said, you need to quantify it.

How unsure are you? 100%? 95%? 90%? Did he just tilt and lose a pot, and now youre facing a shove from 55? How much does that element of doubt change your perception of a 52/48 edge? Even a 5% chance that villain has any overpair turns this into a losing call.

I surfed on over to TwoRags.com and threw that exact situation in...



You've lost $11 on your call. -EV.

Using this, you only show a profit when you are 98% sure. 97% sure is a loss even though its a barely +EV situation. With rake its a loss.




Now, how good do you think you are at estimating between 97% and 98% accuracy? Or should you consider finding a better spot?