I would make the sister an official resident and deal with any real problems that surface. 

What I do, is try to look at the worst case scenario.And it's my opinion, that in the worst case scenario I can think of - where some tenant says their kid or dog got sick from eating soil on your property, I could argue in court that there would be no reasonable expectation for me to "assume" that the property was unsafe - given the fact that the city gave the okay, and I have the documentation to prove it.I would be quite happy with that risk.You can drive yourself crazy over this one, wondering if even if you test the surface soil and find nothing, that there may be some mystery leak buried down in the soil that may somehow rise to the surface, only to end up in the mouth of some dirt-eating child...  

It's amazing how many people use metal utensils on a nice new nonstick cooking surface....or cut things directly on countertops rather than use a cutting board.

Charging the tenant for the first $100 or so in repairs sounds like a good idea on the surface, but it's not.The first problem is that Tenants will be less likely to report maintenance issues.

At the surface it probably seems like I came in and just jacked the rents up, but we asked tenants what their concerns were at the property are.

Just be sure to dive in to the specifics of both before making a decision because of how it may look on the surface.

That is the core of the real estate business.It is true that sometimes tenants who look good on the surface turn out to be bad.

Keep in mind it's relatively easy/cheap to texture a smooth surface, but not the other way around.

If you have two applicants you start with determining first if they both appear on the surface to qualify.

That looks like a screaming good deal to me on the surface.