I have tried to sell several performance cars on Ebay over the past three years, including my 800 HP 514 CID stroker "Capristang" (long story, already told it here) a couple of years ago.
One guy with a similar car for sale on Ebay (92 Mustang LX w/460 SVO engine, lots of other goodies) sent all of my bidders emails telling them that his car was better, mine was junk, etc. This from a guy I'd never met, from somewhere in Indiana. I only knew he did this as a couple of my bidders forwarded his emails to me. One of my bidders also received an "anonymous" email from someone claiming they knew the car, and that it was a "poser" or something like that. I noticed I had no more bids after that interference.
That was my last try using Ebay to sell any muscle cars. I just stick 'em in Collector Car Trader or on my lot these days. In the Trader they end up online anyway.
I did learn there are lots of punks in the Mustang world (yeah I know that's a shock). I still like Mustangs, however.
My wife buys/sells horse accessories on Ebay, and I used to sell Mopar parts there. But as far as selling cars, I think Ebay $ucks. At least it did in my experience.