Make sure on the lease that you indicated that appliances were not included.

This was always the largest factor on which GC's I did business with since its a good indicator of how healthy their business is.  

The most important thing to keep in mind is NEVER say anything that indicates that you know that you know that they are in financial trouble.

The fact they are complaining online might be an indication the property manager dealt with them properly so be sure to ask the manager for their side of the story.I hope this basic guide helps.

Did the company you got the estimate from give you any indication why the house still has foundation issues after it had foundation work done in 2008 and 2012?

That is the leverage.Now to what Matt R indicates. 

Insightful question you've proposed, but I'm not so sure its indicative of the type of investor I am for the following reason. 

Keep an eye out for homes that are in bad shape as it may indicate a tired owner/Landlord.

The landlord sent an email asking if they were prepared to commit to terms, with a lease to follow; the propspective tenant said they would be acceptable, provided that the lease was sent along shortly, and that they were no longer looking at other properties; the landlord sent the lease; the tenant then simply indicated that they had found another property.  

But we all know the best indicator of future behavior is past behavior.