My main goal is large scale commercial properties.  

The location's great (on Main St., near shopping and a college) and it would probably rent pretty easily (once fixed up) for $1100.00/month.

The East Bay is where most of the gentrification in the Bay is happening, with the rapid-transit system, BART, being the main engine of growth for people who want a quick commute into their jobs in San Francisco.

Then when that job goes away the high lifestyle debts still remain.This is why sports figures about 80% of them file bankruptcy within the first year of retiring.

There are predatory sales tactics, predatory insurance practices, construction, real estate, student recruiting, finance, professional sports, all kinds of industries can have predatory practices, even in legal professions.You may not find a statute heading of "Predatory Dealing" you can find plenty of statutes that deal with predatory dealing type matters. :)   

@Luisito Espanola Right now my main strategy is buying tax liens.

A large great room on the main floor which will include the kitchen, a fireplace and two siting areas.  

That would probably help you cash flow as well... but I would still try to avoid levering up the main practice.One other thought would be that if you do acquire the mixed use property I would hire a property manager to run the mixed use building to witch your dental practice would pay rent just like the other tenants.

My main concern is what is your explanation for the high vacancy with below market rents situation?

There is an area called Zona Sul (mainly Ipanema, Leblon, Lagoa) where real states are always a great deal.