What tricky negotiations have you encountered and how did you handle them?

I was wondering how you seasoned investors would handle this situation. 

What we do know now:Tenant has changed locks.House has some issue with sewer gas coming up into the home, which may have happened from property managers husband plumber fixing pipes as we did a huge repair and it started around then.Tenant is now reducing rent by 1/3 legal in New Mexico because of sewer gas.People who we have tried to look at the property to fix the problem have refused to work there because the tenant is freaking them out and talking about lawsuits and looks like she is on drugs.People now keep mentioning drugs to us, but when we spoke to the officials they had no records of tenant other than a fresh eviction before our house. 

I may have to spread out my search though  if I want to reduce competition. 

If I don’t hear from you in the next 10 minutes, I will assume you aren’t attending and I will move on to my next appointment.Using this system as dramatically reduced any wasted time I used to endure as part of the showing process.I have all of these paragraphs set up so I just cut and paste as I get responses.

It may be unfortunate, but trust me it can get much worse if you don't handle it right away.

I have kept this for a long term investment but I wouldn't mind being a bit smarter about how I am handling the property and looking into options.I currently pay around $100/month in FHA MIP. 

A bit worried about if we can handle old houses. 

I had to reduce prices on about 10% of my rentals just to get them filled and even then it was tough.This is why it's important to cash-flow on day one.

If they are deadbeats you may get nothing but I have heard on this forum they they do eventually get paid back, even years later, so it is worth a try imo.If you stick with this company or use a new company be sure to have a clearly defined policy about how non payment of rent is handled.