We all know there are plenty of dishonest sellers out there. There are also sellers who honestly know little or nothing about what they're trying to sell. When buying used gear, you must use common sense and have realistic expectations. If you allow yourself to be "taken", it's your fault. Buyer beware!
I have no qualms about buying used gear under the right circumstances. Been doing it for decades. But I'm smart about it. If I can test the item myself, then I'll know it works. If I can't test it myself but the seller is either someone I know personally or a well-known "good guy" with a reputation as an honest trader, then it's a low risk transaction and I don't worry about it. In my 45 years as a Radio Amateur, I have NEVER been cheated by anyone who falls into either of those two categories.
If I cannot test the item and I don't implicitly trust the seller, then I will attempt to buy the item using these two assumptions: (1) it does not work, and (2) I will likely be able to repair it myself. I offer a "parts rig" price for the item, and if I get it, fine. If I don't get it, that's fine, too.
I will knowingly buy equipment that doesn't work and I know I can't repair it as long as it's worth the purchase price as a parts source for other projects.
Again: Common sense and realistic expectations are the order of the day.
73,
Dean K5DH