I'm thinking about giving loans out to people who offer their accounts as collateral, but how much can you sell an account for? How much does rank, post quality, and trust affect the price? Is it difficult to sell an account?
If you are expecting to always profit from accepting accounts as collateral just forget it. Accounts prices generally always go down because the number available supply keeps increasing, and there are so many ways which you can lose the value of an account (owner scammed before, hacked account, DT user tagged it as changed ownership to you, etc).
It's not very hard to sell a clean account, but some users have starting to take action against account sellers.