And are they doing more harm than good?

I often see this made clear in the short sale package, and if you submit multiple offers to the bank, it will cause confusion and delay...

Interest caculated daily to an outstanding balance can cause different amounts, if interest is compounded and made a part of principal on a daily basis, your loan may not be in compliance for a residential property.Sounds you didn't get the type of loan you thought, I'd certainly investigate the note, your closing documents and especially the APR.

What if they have no money management skills, causing their bankruptcy?

I also ignored the fact that a students apartment with one bathroom might cause a lot of damage.

Look into time of the year as that can cause a 10%-20% change in rental values.

There is a higher likely hood to have a negative cash flow with a 15 yr mortgage which could cause you to lose the property.

Electrical & plumbing just depend on if the are necessary for safety, they won't cause people to pay more.

Get every last detail written down and agreed upon.I am not a big fan of your arrangement simply because it can easily cause long-lasting family disputes.

Someone in that 7% is mechanical failure, so accidents caused by car companies are already happening.