I have a Spin Clean and like it. I use it for swap meet/yard sale records and think it does a pretty good job of getting the gunk out. IMO, it makes no sense to use on new records, though. In that case I wouldn't expect a Spin Clean to make any sonic difference which might explain some previous responses.
What is your experience with the Spin Clean?
Mine is it makes absolutely no difference. I'm thinking about returning it.