Once this happens to me in an area, I am not inclined to repeat my mistakes, or to put together deals that I can't make stick. 

Mistakes are part of life and the rate of mistakes increases anytime we undertake a new venture. 

I think it's a mistake to ignore or dimiss those tenants that are chronic complainers and those that are constantly thoughtless and/or worse rude to neighbors (garnering a steady stream of complaints) as not a landlord problem.

Please keep in mind I'm not saying these things to criticize you (although it will sound like that) but in hopes that OTHERS CAN LEARN FROM THE MISTAKES YOU MADE HERE (and trust me I made them all before too)so that he could stay and try and get back on his feet financially.

If you don't know the market before you go to buy you might make a big mistake.

Because of this one mistake, she made no money on her flip.

Or am I making mistakes in my calculations?

I made the exactly mistake back in 2018.

I'm wondering is this normal or did I make a mistake?

His unwillingness to fix his mistake shows just how terrible he is.