You are right about the blacklist, however, it's very unlikely you will have legitimate users coming from datacenter IPs. I've used this trick to prune hundreds

You are right about the blacklist, however, it's very unlikely you will have legitimate users coming from datacenter IPs. I've used this trick to prune hundreds/thousands of bad accounts in a couple of forums. You need to be careful with it, but I think it's a worthwhile method.