Under certain circumstances, an appraiser may apply a gross rent multiplier for valuation purposes.

The circumstances of the seller, their motivation is part of the negotiation process, however when you are buying real estate, playing on the misfortune of others more than aligning your offer to the true value of the property is simply predatory dealing. 

As for other liens that survive, these can be: IRS-under special circumstances (under 120 day redemption period from deed recording).

...Charles, I only recommend out of state in two circumstances.  

People throw opinions around BP and can put others in harms way due to ignorance.Yes, in rare circumstances, adverse possession may fit the bill however it's the tool of last resort. 

As far as I can read your circumstances, that does not seem to apply to your "facebook friend" (buyer bird dog) or your "connection guy" (mucha moula)?  

There is no whizbang system, each deal stands on its own, they are hard to duplicate due to the circumstances and the situation a hand, learn to identify the possibilities

There's really no good evidence/link anyone can provide as these are merely speculations - given the long bull market run coupled with "circumstances" they deemed reminiscent of what happened prior to 2009 dip. 

People have life circumstances that require them to make odd choices.

If so, under what circumstances?