Once upon a time, using RBLs to drop mails was actually a good idea. These days seems it is no more possible for a reason or the other, so every one switched / is_switching to just use RBLs as another test in score based antispam solutions (read: SpamAssassin & friends).
This gives good results, but neglects one of the benefits of RBLs, namely the ability to reject (supposed) spam before even receiving the message body.
Is still there any RBL that makes sense to use that way, to hardly reject anything that fires a match in that list? If there are people doing it that way, do you ever get false positives due to the list?