I would argue your second statement in A) assumes that a movie can objectively be rated good or bad. Plus it also seems to claim to know exactly what people want to see from a movie. Never s fan when someone seems to say, "I know better than you do what you like."
I'll agree a trailer doesn't always do a good job. But to claim a person can't tell if what they watched is good is hardly a statement a same person would make. Possibly a narcissist would say it. Or someone else full of themselves.
There is obviously technique that can be graded, but that doesn't make a movie.