Do you tell people their watches are frankens?

I think making comments on seller advertisement is wrong, unless its fake. Buyers should do their homework before making an offer.
That goes for everything.. watches, luxury goods, art, cars etc.

Making comments on a forum is different.
F.ex; If I bought a watch a while ago and did after best ability thinking it's genuine. I would'nt mind if you told me the crown is not the right one for this model.
Then lesson learned.