CrashGordon94

Some stuff they have a limit on how much they will take, presumably to stop Scrap having too many of an item they can't effectively sell.

Now this is just a guess but I figure it might have something to do with struggling to find acceptable price estimates to put on those categories of item. There's also two cases that bring up different messages but have the same effect: 1) You can only bid things that have a certain amount of value, after factoring in Item Factor percentage. Can't fully explain this one but probably to push people to only give stuff worth having or selling. 2) The auction holder can chose to block skins and War Paints. These are harder to price and sell so it makes sense why someone might not want them or not trust that they're worth the price the algorithm gives them.

I think the oddball keys are under the miscellaneous item section, with paints and such, were you checking there?