I've been a seller on Ebay for a long time for a small local family owned pawn shop for years now. I do my best to check out, describe correctly, clean and properly list the things I sell. I mostly don't care who buys from us and what they do with what they buy. Resellers is just part of the business.
However, making up lies about my products, like saying they're dirty (again, I clean everything) to not only return them, but to return them after they've been resold on AMAZON, re-shipped multiple times, and then to get it back damaged and opened is super scummy.
It is also against Ebay's terms of service to sell other sellers stuff on another platform, and then abuse the return services.
Either way, I wouldn't buy from or sell to this person. They are sketchy and scummy, don't communicate at all, and abuse Ebay's services.
Best of luck if you have to deal with this butt nugget.