I don't sell much and not as a business but I'll only sell on Audiogon .
As I remember, when a person makes an offer his name, address and real email comes up. I verify as much as I can online, that he lives where he says, I LinkedIn him or do other searches to make myself happy with his bonafides. If not there yet I will email and state that I would like to talk with him.
The persons I have talked with have been happy to discuss these things, as I am making myself happy with them, there are likewise, and who doesn't want to talk about an item they are buying?
I am not talking about for a small ticket item. For the one bigger ticket item I sold recently I actually weeded out several scammers. Definitely seller beware.