Since I've seen the market and all the spam of terrible deals you have to wade through to see if there is anything of value, I had always thought it would be ideal to allow players to hide bad deals permanently just on their own screens.
Let people mark the offers as bad deals (spam) or just as items that they aren't interested in right now (not spam). If enough people mark the same offers as bad deals (spam), hide or remove the offers for everyone, or put those offers under a separate "marked as spam" section. The offers marked as "just not interested" should go into a separate section as well so the player can come back to it at a later date if he or she needs to.
This will let players organized and clear out their own lists so that they can easily browse and categorize new offers. And in the process, they will help to clear the spam for everyone.