Not an item that would be used for HVAC work but I bought a Fluke Scopemeter that had several lines in the display that changed every time I turned it ON. Seller claimed that USPS damaged it, filed a claim, USPS claimed no damage to the shipping box or they didn't do it, guy strted to get nasty when I asked for a refund, started a dispute on eBay, had to get it evaluated at a repair shop, I finally won and got my refund.
I then got a real nasty email from the seller with all kinds of name calling to me and the shop that tested it.
Ive bought many tools off of ebay. From nutdrivers to vacuum pumps. I always buy new in box and have had no problems. Just watch the shipping costs sometimes youll end up paying more than if you just went to supply house. Also check their feedback before committing.
What makes me wonder is when it seems very cheap. For example fluke 87 for $100.00 . It's almost with the gamble to save 400 bucks. I have seen several items like this though. It is used but. I guess you just don't know unless you try. Sellers have 99% positive feedback so. Has anybody had a problem and then not been able to get there money back.