Under the circumstances, I think you did the right thing. People who put the effort into perusing ebay in search of an expensive gen are not going to appreciate your rep, no matter how much you chat it up or how beautiful it may (at first) appear (prior to an admonition that it is in fact a 'fake').
And I do not know how many times this has to be repeated, but the average gen buyer/owner knows little or nothing about watches (and I am speaking of watches in general, not just the Daytona). This guy has only a vague idea what a Daytona looks like (from a few grainy pictures he saw in the Wall Street Journal or after catching a few glimpses of one of Donny Deutsch's). The only thing he knows for sure is that alot of people with alot of money seem to be flashing them around & for that reason alone, he MUST own one too. This is exactly the type of guy who gets ripped off by scammers selling fakes and frankens on ebay, because he spends his time making the money required to buy a gen instead of spending his time learning about them. Rarely, do people have the time (or inclination) to do both.