LP grading has ALWAYS been a problem, always. When it was a face to face retail transaction, the usual system was if a record 'looked good' to both seller and buyer, if it turned out to be bad, the seller would (hopefully, at least for regular customers), take back the LP. When internet sales came along, the problem became more complicated, with newbies mistakenly misgrading LPs, and scam artists ripping people off intentionally. On eBay, My experience made me just quit using eBay as a way to buy LPs. (As for the goN', I find most LPs very overpriced, or overgraded.)
The grading problem is only solved by buying ONLY from those sellers who have a proven track record, and that means paying more.
I cannot see how an honest rating of "bad, but worth collecting" for a rare record is a fraud? I have sold an LP listed as $500. mint (mine was not so good, I sold it to a local dealer for $25., he had never found a copy of it before..) So was I bad?
The buying of 'pig in a poke' LPs is part of the process.
When I hear folks wanting to 'get into LPs' I ask them: Do you have a LOCAL SOURCE for LPs? If not, it is pretty tough to get back into buying LPs. (unless one is wealthy).
I (lucky me) have over a dozen LOCAL LP sources..
I already re-collected 14,000 a few years ago, then 'threw back' (to local second hand stores) more than half when I had to move. Now I have about 6,000 plus LPs. And I buy only locally, and only perfect looking LPs. A mark on the surface means no sale.
I no longer waste time searching second hand junk stores for that one in a thousand find.
I did, when I wanted to, but that source is drying up fast.
If you really want to find LPs. Go to the estate sales in your area.. the FIRST day. Sooner or later you will hit the jackpot.