Is there a reason why folding here is so bad? Like I mentioned in my earlier post he has to be bluffing here at least 25% of the time before we start showing a profit for calling down.

Is a 35/11/1 player really bluffing or playing a weaker hand then us here more then 25% of the time?

I have been calling down these and Villain almost always (much better then 75%) is showing down a hand that beats me.

Can someone explain a) why folding is so bad when we have an overpair to someone in a small-medium sized pot on an un-coordinated board who is check raising us on the turn with an AF of 1ish and b) whether my 25% for calling to be successful is correct.