noelf2, you may be correct.
Like I said, though, I have never received such answers to queries about a potential purchase. Part of me probably did want to make a statement.
Part of me actually thought it might really help the guy to know 1) that it was a series 80, should the question come up again; and 2) that the way in which questions are answered may very much affect a sale, for good or ill.
I have been asked questions to which I had no answer. In such cases, I have let the potential buyer know that I would try to check, and then answered once I found the answer.
In one case, I could not find a definitive answer, and told the buyer that I could only make an educated guess; I then sent him more pictures so he could try to make his own determination.
Maybe I am unreasonable, but I think courtesy should be the norm, and not an occasional, pleasant surprise.
Edit: noelf2 - with regard to expectations, an apology for the sarcasm the guy threw my way about reading a serial number, when in fact he had not put it in the ad, would have been in order.