[tigerite]

I'm sure you know this already but yes, there certainly are situations when you should call as a 50/50, and even as a 45% dog and worse. They're rare but they do occur.

To give an example let's say you're in the BB with A8s and the SB has pushed. If you fold your EV is 0.1556 (and the SB's goes up to 0.1556 also). If you call and win your EV goes up to 0.2716, and the SB busts, thus 0. If you call and lose, your EV goes down to 0.0475, and the SB's up to 0.2430. In this case, you only have to be a 49.6% favourite, and can call as a coin flip, even assuming you want a 0.3% edge.