I'm just looking for fish hooks that may be pertinent in the USA as I am a kiwi so not always au fait with some of the differences in the USA.

And I really did not want him as he is a registered violent sex offender against children, a renter whose background does not meet my standards. 

Then I had someone come back as a registered sex offender-- nice guy, good references, plenty of income.

Provide them with neighborhood crime reports, sex offenders in proximity to the property, necessary repairs, foreclosures in the area, cheap comparables, any signs of distress in the neighborhood (vandalism), news-paper clippings with bad local economy news, etc....It would seem the ideal model might be a lower 1st with higher 2nd?

Someone with a criminal history (felony, misdemeanor, sex offender, etc)?

If you are using a property management company make sure to tell what kind of tenant you want (FICO, income to rent ratio, section 8[I don't recommend],prior evictions, criminal history[sex offenders], marijuana on property)If your unit is a studio or 1 bedroom you can a lot more money wit Airbnb, most markets now have Airbnb property management that handles all turn-over things such as cleaning, dealing with guest, we use and August Smart lock that sincs with Airbnb so you can see on when they come and leave plus a security camera outside the unit to make sure there is no extra people or a party going at my unit so far we are making more than double from what we use to make on it with a regular tenant.

We are instructed as investors and real estate professionals not to discriminate based on race, sex, religion, day of the week of birth, etc. 

If they do and damage or crime (ie registered sex offender) and they were living in your property and something happens you could be held liable and it could be a slippery slope that we don’t want to go down.

Nationally (protecected classes highlighted):In the Sale and Rental of Housing: No one may take any of the following actions based on race, color, national origin, religion, sex, familial status or handicap:Refuse to rent or sell housingRefuse to negotiate for housingMake housing unavailableDeny a dwellingSet different terms, conditions or privileges for sale or rental of a dwellingProvide different housing services or facilitiesFalsely deny that housing is available for inspection, sale, or rentalFor profit, persuade owners to sell or rent (blockbusting) orDeny anyone access to or membership in a facility or service (such as a multiple listing service) related to the sale or rental of housing.Fair Housing--It's Your RightLocally there can be others.

You can also see population trends, # of sex offenders, and lots of other information.