As you see, it doesn't change anything: I will be downvoted, then sued, then jailed despite my beliefs.
Buying a Rolex from some guy in a car park is different to buying one from a jewelers. The former wouldn't protect you in any way, the later would let you demonstrate a good faith belief that it wasn't stolen, and wasn't fake.
More generally, say if wanted consumer protections consistent with it being a Rolex, or if you wanted to sell it as a Rolex. Then whether you bought it as a fake does matter.