The first one really suffered in the compression for the auction...avoiding the supersize feature would help it a lot.
The auctions that didn't use supersize looked a lot better to me, as did the "supersize" version of the photos.
Some colors do worse than others when you compress them. Another factor is how you compressed them first. They are getting a few doses of it between what you do and what the service does and that can make for some funky results.
I suggest making your pictures a reasonable size and using them full-size. Do a closeup of, say, the drawing on the page rather than show the entire page, complete with huge red background, for the supersize version.
(Note: I don't sell what you sell...so these are generic suggestions and may or may not work for your niche.)