They will ruin your rental and tick off the neighbors at some point.  

Stated income, no document loans, 580 credit scores, no income or employment or asset verification, etc. were collectively the primary factor behind the great recession - which ruined the lives of tens of millions of people, including my own.I should say though that FHA loans are nowhere near as popular as they used to be, most likely thanks to their excessive insurance premiums.

I have seen family members fight over loans, I sincerely hope it will not ruin your relationship.

MFH multiplies your management responsibility; what you gain by having one roof and one location you subtract by being involved with interpersonal relationships, as there will always be instances of tenants not getting along, ruining the atmosphere for everyone else, etc. 

It's very cheap ($1 / ft for materials), it looks nice and renters don't care, and it's easy to replace when they inevitably ruin it.

Because families tend to rent big units so it makes them less risky compared to single adults that may ruin and not take good care of their living space2.

I could have ruined all of our things, I could have been hurt chasing raindrops in the dark in the attic...who knows what could have happened. 

If not, we could have easily ruined ourselves financially. 

That's a very good way to waste a lot of time, ruin your credibility among your peers and never get paid a commission. 

And it can ruin your finances, and budget for years to come.