They do, but sanity checking code is fairly hard. Some work has been done on properly sandboxing and securing JS code (ie, the Google Caja project), which I be

They do, but sanity checking code is fairly hard. Some work has been done on properly sandboxing and securing JS code (ie, the Google Caja project), which I believe works quite well, but Ebay doesn't do any of that. Instead they crudely scan through the listing with a simple regexp looking for keywords that they think suggest you're doing something nefarious. Eg, any JS that looks to them like it deals with setting or reading cookies is flagged; anything that looks like it opens a popup is flagged. "For every complex problem there is an answer that is clear, simple, and wrong."