tedster - 1:41 am on Jul 27, 2012 (gmt 0)

Here's the big issue with your idea. If you treat googlebot differently from other visitors, then you may get slapped with another penalty - for "cloaking". Whatever you do here, you're going to need to treat all requests the same. And by the way, Google has been following meta-refresh and javascript redirects for a few years now, and they even send link equity through such redirects.

Are you sure there are visitors coming to these URLs with the bad backlinks? Couldn't you just serve that content at new URLs without doing much damage?

Also - roughly how many URLs are we talking about here?