Clarkmeister theorem checkup, among other things

Wouldnt the thereom be not applicable when your hand likely beats all non-flush hands?

Furthermore, if someone made a non-nut flush on the turn, and the pot gets big, they almost never seem to fold it to a river donk. However, on the otherside of things, if they stumbled upon a weak flush on the river, there is a chance they will fold it, albeit a small one.