Before returning to Audio, I was buying and selling watches. That hobby is even worse than audio.
Though wire transfer is considered safe, crooks know how to evade the system and screw you even when you use that.
The best advice is to use common sense and if you are suspicious, to ask the seller to send a photo of the item with something identifying-like your name, date or the front page of a national newspaper.
Pay with a credit card or paypal (not Friends and Family). References are good, too.-But, someone starting out won't have ref's, and that doesn't necessarily mean that they are scammers. Face it, we all had to start somewhere.
If the seller has no feedback, ask to call them. A short conversation should give you a sense of who they are. In my many buys/sells, I have found 99% of the people to be honest.
And, buying here on Audiogon offers some very good protection against getting ripped off, as Tammy usually sorts things out.
Bob