A non-violent crime from almost a decade ago should have no bearing on your approval to purchase a condo unit.  

Collecting rent in person from violent felons; what could possibly go wrong?

That policy would have "income > 3x rent", at least one good landlord reference (don't neglect to actually contact the reference), no evictions, no violent felonies, no foreclosures...etc.

One a violent serial rapist, the other the same, but for minors.If they are tenants, one thing I learned is if they are not under a lease, raise their rent with a 60 day notice to a few hundred dollars over the going rent for the area. 

You can move the property into an LLC to shield your identity.Bad, angry, violent tenants threaten landlords.

Police are under staffed and unless it's a violent crime like murder they consider you a nuisance asking them for help..

First read your local laws - it may be that you can not deny an applicant for criminal conviction unless they are  violent or monetary .....  

In the years I had it (and according to EPS 90 days before) there hasn't been any violent crime in the area before. 

For example, the claim that undocumented immigrants are associated with increased violent crimes has been debunked by nonpartisan studies, as has the claim that undocumented immigration is associated with increased drug crimes.A landlord who makes rental decisions based on such generalizations could run afoul of federal and state housing laws.

The negative energy emitted by such places tends to be of a more violent type, perhaps associated with killing and death.