If the backyard got that overgrown and the neighbors did not complain, maybe their yards and behaviors are worse. 

I would be apprehensive on history of bed bugsI would say no if a previous landlord gave me a bad reviewand anyone in the world who threatens me out of some perceived moral high ground in an effort to intimidate me so they can get what they want at my expense, well they are surely to receive only my most vile behavior in return.I wouldn't just turn this person down, I would ask to meet in an empty parking lot and fist fight. but then again, that's just me, and I'm feeling particularly hostile today. real answer: you should pass, and stop communicating with this person

Also, a reason not to accept a security deposit from a nonprofit or social service agency is because if you get into a conflict with the tenant, the organization will "advocate" for them, including legally, and may be quite absurd (and incorrect) about the level of "rights" they claim for the tenant, and this is super stressful, and also, now you have a very entitled tenant who thinks you're obligated to put up with all sorts of awful behavior- because they've been erroneously led to believe that they have excessive "rights."   

Based on the sellers behavior, I'm guessing there probably wasn't actually a deal there for you so it's good you got out quickly.

If a tenant texts you at 11pm on a Saturday and you respond at 11:05pm you are training them that this is ok behavior.

When someone blows so much smoke and is so quick to get nasty & personal instead of addressing the substance of the discussion.....well, such tawdry behavior reflects poorly on that person's judgment & credibility. 

Whenever I go to the marketplace, one particular listing is always on top. Its subject line is:!!!! West Philadelphia Triplex Off Market Listing !!!!All subsequent listings appear to be in order by last update. Did th...

What about other aspects such as desirability from location on the street, how appealing the entrance or display window is, restaurant vs office space, etc?

It teaches them bad behavior and ultimately they will get evicted by you or some other landlord in the future.

when you never take responsibility for your actions and blame others that is I think is sociopathic behavior its all about how they have been harmed..