it would be nice if google gave us a decent tool to check domains before we bought them. Currently they hide most (>90%) of back links.
It's a nice idea, but will just make the spam problem worse.
For example, when Google first started the Panda updates, I read that some sites were being targetted via paid link buys NOT purchased by the actual owner. Would be nice if there was a tool that let the owner find out that was what was happening to his site.