I was told once that Gordon Heights has more registered sex offenders than registered voters.  

Not sure what you mean by level of technology but I have used theses sites to research a city/county City DataWest Allis, Wisconsin (WI 53227) profile: population, maps, real estate, averages, homes, statistics, relocation, travel, jobs, hospitals, schools, crime, moving, houses, news, sex offenders (city-data.com)andWest Allis, WI Real Estate Market Data - NeighborhoodScout

As long as you're not discriminating against someone based on race, color, religion, sex, national origin, familial status or handicap, you won't run afoul of the federal Fair Housing laws.

Title VIII of the Civil Rights Act of 1968, as amended, prohibits discrimination in the sale, rental, and financing of dwellings, and in other housing-related transactions, based on race, color, national origin, religion, sex, familial status (including children under the age of 18 living with parents of legal custodians, pregnant women, and people securing custody of children under the age of 18), and handicap (disability).Better take a landlord class and get your act together.

- To be absolutely clear here, we have no issues regarding race, sex, sexual orientation, or religion, or anything of that nature.... but we would strongly prefer to not rent to a family with young children.

Then I heard about the (unfavorable to men) sex/dating ratios in San Francisco.

And if you want to be in the housing provider business you can not discriminate against individuals based on their race, color, national origin, sex, familial status or disability.

"Fair Housing Act".....did you ask for their sexual orientation, age, sex, race, religion, marital status....etc? 

This can include credit score, nationwide criminal background check, sex-offender list check, international criminal check, and eviction history (so any public records or information that might be connected to legal court proceedings would be pulled back as well).

Otherwise wait until the agreement renews and make renewal contingent on that.If ti is a single family I would probably just look them up to see if they are a registered sex offender, otherwise just let it go.