Why would the cop arrest him...???
Basically there was no evidence of money exchanging hands, so there is therefore, no evidence of solicitation whatsoever.
It makes the cop look like a complete idiot. Are there idiot cops in real life. Sure. But I think the movie should have established this since he is suppose to be a trained police officer who is trained on getting real evidence. It just would have been much more convincing if they showed a scene of the cop having his ass handed to him, by the captain.
The captain would say, "Why would you arrest a mentally challenged man who didn't even exchange any money with the hooker!", or something like that. Just to make the dumbness of it, more convincing and acknowledging it. And I think that Sam's lawyer should have proven to the court that the cop was attempting to frame him on a false arrest with no evidence.
I mean if I were put in Sam's situation and a reasonably goodlooking woman, who looks a lot better than most prostitutes you see you on the street, and who was showing some cleavage came to hit on me, I might respond positively at first and I am sure lots of guys would. And a police officer knows perfectly well that it's legal for a man to be picked up by a woman, and there is no laws against it, before any money exchanges for sex, takes place.
What do you think?