Generally, no nightmares, because I told all potential tenants right up front, “I am calling your prior landlords, I will not accept any evictions or criminal background more than the occasional speeding ticket”.

When I rent to applicants I consider what they tell me and then verify with Credit and Criminal Background checks. 

In fact in my state they can be charged with a criminal offense if they do that.

If there is minimal or no criminal history or negative history to speak of, it usually produces the report within an hour or two.

The most stringent screening process still can't guarantee you won't run into this again, but certainly can help you mitigate some of those risks (ie. be sure to include a nationwide criminal background check, eviction history, credit score and credit history breakdown, and reference checks from prior landlords).

No offence but I have yet to come across anyone that knows what they are talking about on BP when it comes to lead gen!

Sure you probably won't get caught with <$5,000 of deductions, but its not scalable and could have criminal or civil suit ramifications at the extreme.

No offence but I find that hard to believe. 

However, like insider trading, some are detected and end up as either civil or criminal matters.

I also find that optimistic, hoped-for pro forma rents coupled with hidden concessions that drive low vacancy is a usual trick by criminal brokers.