I've shaken a few undesirables out of the tree that way before I made a mistake with accepting them. 

Now you have the visceral experience of signing your name on the bottom line and being responsible for this large asset.You also had your first experience with an undesirable tenant. 

Chasing yield will lead you to undesirable areas, where you're not ready to deal with the issues. 

Since we're buying as a partnership, having some kind of personal guarantee is complicated and undesirable. 

I was able to ralley the owners and get them to agree to assessments for rehabing the complex and squeezing out the very undesirable tenants and owners

Possible options I have considered include:leave things as they are since things are going smoothincrease the rent and get sued if my research isn't correct increase the rent and keep the tenant month-to-month, with the risk that tenant may decide to leave and I may get an undesirable new tenant  along with costs to clean/paint and update the unit between tenants increase the rent and have the tenant sign a lease, otherwise move out.  

It may very well be, but I'd guess that this behavior is recognized as undesirable for lienholders because no one will bid the properties at the auction because this sort of behavior discourages it.  

Google Craigslist ghost postings.all caps some keywords multiple postings with the same text will get ghosted meaning they let you think you're posting but it actually doesn't become visible.this is Craigslist attempt to weed out undesirable content to increase the quality of their content.

But if someone pinned me down with a gun at this moment, I would say A property is high neighborhood, high desirability, B property is good quality working class neighborhoods, C property is lower middle class and fringe neighborhoods that are either just declining or are just coming back, D property is lower class property in undesirable areas but houses are still standing, and F is war zone material.

Great pickup for you, very poor investment for him.We have this discussion at work all the time, and I have first hand experience where Australian's got sold turnkey properties in highly undesirable locations in Cleveland and they lost all their money.