After too many bad experiences, I rarely buy used online anymore. When I travel, I make a point of checking out every used record store in that city. I take a list with me of records I am keeping an eye open for. It is a lot more fun this way and I always end up discovering a lot of records I didn't even know existed.
This was my thread from a few years back regarding my frustrations with discogs. The final straw was reading that allegedly some big sellers on discogs can get their negative feedback erased. Perhaps, it is the one you are referring to?
https://www.audioaficionado.org/showthread.php?t=36508