It's hard to remember when it happens, but if you persist, you're going to make a lot of money off lessons learned in RE.

I was on the market like a hawk though.Im not sure if I got lucky, or if I just happened to be persistent.

Now my tenant -- who is in arrears with the water department -- has told me he expects me to pay towards bills that he says were too large dating back two years to when he moved in, saying that it was obvious that the issue persisted much further back.

Persistence will pay off in deciding that those really are the people you want to work with.

I'm sure there is a fine line between being persistent and being harassing, how do I determine that?

I will stay persistent.

Exception: if the tree was obviously damaged/diseased and the other party gave them written notice of it in advance.

It sounds like you are infected with a very expensive disease I call the "hardly waits".How do I know? 

Always remember to persist and you will WIN!!

Every lot I have saved to show him is literally under contract with in days I unfortunately was diagnosed with Lyme Disease the Medical Costs outrageous.