IF I was going to buy a timeshare

I know to look in the secondary market. But what else do I look for specifically?

I know of the evils of timeshares, and I am NOT looking to buy one. However, I do notice on Ebay that some go for a few hundred to a couple of thousand dollars. Even amongst the shit, if one digs hard enough one can find a diamond. So I was just wondering, IF I was looking what aspects would I look for.