Quote from @Matt Lindsey: If they suspect mold is irritating them, they should start by performing a visual inspection of the home to see if mold is present.

Its quite irritating does this happen often?

I find it overwhelming and irritating that the program doesn't have like a beginners, intermediate advanced area. 

Also, if you get a negative IRR it means your cash flow didn't pay back the initial investment.12% IRR is a good return.  

I could be wrong, but that's the assumption I use to make my decisions.As far as cash on hand, I typically assume I can make a 5% return for no risk / no effort (savings account) and around 12% for moderate risk, lots of effort (basically finding another property to buy that pencils at 15% irr).Now that we've got those two difficult assumptions out of the way, the question becomes, how do you calculate IRR?It's

While higher free cash flow will boost IRR, it is not the only factor for returns.

It really irritates me to see how the staff treat them.  

Among other things, prolonged exposure to the smell of ammonia from cat litter can cause coughing, nausea, irritated lung membranes, eye irritation and abnormally high heart rate.

I find it overwhelming and irritating that the program doesn't have like a beginners, intermediate advanced area.

IMO, rent increases are viewed as harassment and easily irritate good tenants.