As we started to rip flooring up we uncovered other problems etc. 

Did you get a pre-inspection to uncover any issues or did you wait until after it was under contract?

Philippe- In terms of large assets I would venture to guess the "future buyers" of a resale would be able to uncover the end of a PILOT program in their due diligence period.

Generally people with zero rental history could be real, or they are hiding something, often social media will help to uncover those things. 

You may uncover some repairs that you weren't aware of prior to purchasing, non-performing contractors, etc. 

I'm reading (or, in this case, listening) to "Never Split The Difference" by Chris Voss, one of the things he says is that in any negotiation is the "Black Swan" the uncovered reason for the action.

Phrasing it that way allows you to just start a conversation and uncover their motivation, or lack thereof.