Any time someone says "I know a lot of people in X and they are saying Y" it usually means the fact is either made up or massaged to make your argument.

Feel free to massage me. 

I think @Jeff S. nailed it.If you were determined to buy this I'd give some thought to a small office cluster for therapists/ practioners like counselors, massage therapists etc.

I'll have him work on a product line of solid inexpensive massage/stretching devices that primarilly function by floors, walls, ceilings, doorways and basic furniture that has been passively developing in my head over the few years that I've been dealing with a lot of stress related muscular pain, not to get personal but maybe I may have run into this fellow for another purpose than so far assumed.

Your SFHome or apartment isn't zoned for business,, if they have anyone coming to residence for that purpose,, hair cutting, tattoos, tax work,massage parlor, drugs, or daycare,,,,,, its gonna be a issue..  

I am currently going to school for Massage Therapy and will graduate and be licensed hopefully by August.

Some investors in the beginning factor out that cost to massage the numbers to talk themselves into buying a certain property as they are frustrated finding deals so start bending their underwriting criteria.

Currently I work as a Licensed Massage Therapist.

You just have to get the old tenants on board....and massage the message, so you don't lose your good tenants.  

Tenant was using this as an illegal massage parlor.