FastEddie, sorry to hear someone was bad mouthing you. I can honestly say, from the references I've called over the years, I've never had someone bad mouth anyone but I have had employers tell me a person is not eligible for re-hire. I hope you were able to resolve what ever the issue was with the other person and have them stop bad mouthing you.
Nobleman, credit report...no, never heard of one...yes, I have heard of them and yes, candidates do sign paperwork saying it is o.k. that we look into things one has stated on an application. You are correct 3rd parties will make the calls or do the research to ensure the candidate is being truthful with what they stated on their application. Why would anyone, not just a company, want to deal with someone who is making false claims?
What you stated are not companies that keep a list that call out someone to never hire them, 'blacklist', rather ways of confirming information that someone has stated.
TJR, the quote you found is correct. A reference/previous employer can make factual statements. If that means, the person was always late, didn't meet deadline etc.. and have the proof this took place, they can say that without having violated any laws.
Good luck to those looking for new employment, I hope things go well for you.
Marc