@Kristyn Grimes One common weakness I often see in landlords' leases is the way they handle their late fee.

There's a big difference between someone with bad luck and a chronic complainer.

I have a weakness for old houses. 

If someone wants to sign a lease but doesn't have the move in funds, this is a red flag right from the get go as it demonstrates they have weak financial planning.

In general, a physical or mental impairment includes hearing, mobility and visual impairments, chronic alcoholism, chronic mental illness, AIDS, AIDS Related Complex, and mental retardation that substantially limits one or more major life activities.

@Katherine Rossell - Next property, either stipulate it's empty when you close (if you know the current lease is weak, which you should have here) or if you think any of the tenants are trouble in any way.

My strong suspicion is they are taking advantage of the current weak owner and they know they are getting a free ride that they won't get anywhere else, and that the ride has come to an end. 

I should have taken their late rent seriously after the second month they were late... they are definitely taking my kindness for weakness.

If you show weakness and back down to the tenant's threats, they will walk all over you - and it may also be used in court to show you allowed the behavior, so now you can't complain about it.

It sounds like you have compassion, and they smell your weakness.