It depends on:
A) Whether I like the shop/seller in question, and therefore do or do not want the seller to make a sale; and
B) Whether I perceive the buyer to be someone who is likeable. If he seems like he's intelligent and likeable, and/or cares about the RKBA, I'd probably help out. If he seems like duckhunter type, who could care less about the 2A, then I probably would not help, as I have nothing but utter contempt for those types.
"...as well as your proficiency on how to perform malfunction clearance drills."
Lol - while true, I'd have to say that you must be one of those "glass half full" people.
Generally, I'd keep quiet, as someone else mentioned, unless a misrepresentation was being made.