I also can confirm what was said about mega sellers. They somehow have the ability to wipe their slate clean.
I bought several locos with no boxes. In my payment, I even urged the seller to carefully wrap each one since there was no box. What I got was a sandwich bag with all of the locos thrown in rubbing against each other.
I waited for positive feedback posted on me first. Then I posted neutral feedback since no real harm was done, but it was pretty sorry packing. Seller posted an ugly reply to me.
A couple of days later, the rating was magically gone. The comments were still there, but the rating was poof!! gone.
I received nothing from ebay about a dispute from the seller.
The lesson I learned is that ebay protects the mega power sellers. The rest of us are small fry. Ebay does not want to lose the big sellers since it is THOSE guys that pay ebays bills, not people like me.