I agree because it seems to me, even if they WERE faking it and didnt hurt that day, who are we to determine if it's faking or real? I mean, we're not them, we can't feel it. That said, I actually do think faking in some situations us possible even though I mostly agree ginger and bunny. For example, if they hurt badly one day and they got out of work for it, a very smart horse might learn that all they have to do to get out of work is do that again. It's not necessarily deceptive but a learned behavior. For example, one time I had a lesson on a day where but the horse had been ridden that morning by someone looking to lease him. She was older snd I guesz had kinda rough hands or jerky or something and for some reason he haaaaated her so he did this little bucking behavior, not real bucking because he was like 24 and too old, but like a half buck thing. Well anyway, she got scared and stopped working him and got off. So when I had my lesson later, he tried it a bunch with me because it had worked that morning because she got off him. I didn't nd just worked through it until eventually he stopped doing it and then we had a beautiful rest of the lesson. Now, when I first started riding I probably would have been scared but I had been riding there for a little while and rode several of the horses. I haven't ridden in like a year plus now though

but anyway, who's to say a smart horse couldn't figure out certain behaviors work to stop riding?
Now that said, like was mentioned, horses are prey animals and don't just show signs of pain, prey animals would have to be pretty in pain or sick to actually show it.
So even if they were faking, I personally would give them the benefit of the doubt rather than risk hurting them more. That or I'd get someone experienced to look at them or both.