Moral Dilemma: what to say about terrible tenants when asked?

[Johann Jells]

Do you ask applicants for their current landlord's contact info? I do, but never call. A few years back I was put in an impossible spot. I was evicting a rotten couple, not an easy thing in NJ but I got lucky, and they showed up in court with a City social worker who said that they had a new place lined up but the eviction was keeping it from going through. I was asked to rescind the eviction and write a letter saying it was all a misunderstanding!  If I didn't it appeared that I would never get rid of them. I was basically being blackmailed. So I swallowed my pride and did someone a bad turn by giving them these horrible tenants. What was I to do???  

Ask for the contact info of the previous Landlord.