I have bought and sold cars, boats, jetskis and even holidays on ebay and I like to think I can spot a "muppet" from the way they communicate. If they type in text speak or just launch straight into "how much will you take" etc then they are almost certainly a muppet, if they start the message with a greeting and sign off with their name then I think that is a strong indicator that they are pretty decent.
I have met some great people from ebay, last jet ski I sold on their is now in New Zealand, bought by a guy who flies over twice a year to buy as many 6 berth caravans as he can get hold of, fills them with rolls of loft insulation and loads them into sea freight containers, he then puts in a couple of the two stroke jet ski's to fill the container as all these items sell for a fortune in New Zealand.
Darren