"Let's be careful out there."
As a best practice, I always work to engage a seller in a substantive conversation about their gear, audio in general, what have you. Scammers are not usually capable of holding that conversation in a way that doesn't raise red flags.
So by the time I've purchased something, I usually have a pretty good sense of who I am purchasing from, unless they are actually both audiophile and scammer, which isn't particularly common, I don't think. Plus I've had some pretty enjoyable interactions.