A) It's obvious, especially after viewing multiple posts by that user.
B) The user is taking real photos of other women, then photoshopping on his wife's face (at least I assume it's his wife, who knows! could just be some women he lusts after) onto the other women's bodies.
C) Although I'm not an expert at digital editing, I am an experienced photographer and can easily recognize the more obvious indicators that a picture has been faked.
Exactly. If someone says "hey look at these fun images I created" then that's all good. But when you're flat out passing off photoshopped images as the real thing, then I'll call people out for it.