The idea that this professor suggested such nonsense to impressionable youth seems criminal to me.

Then why does this not apply to eviction records, criminal records, income amounts, etc?

If mom and dad allow their 20-year-old son to live with them while attending college, I run a credit/criminal background on Junior and make sure he is on the lease.

Squatting only becomes a criminal offense once the actual owner has established they are no longer welcome.

For example, I mention that every adult must pay a $30 application fee and pass my credit/criminal background, they must make a combined income of 3x the rent, and whether or not the property accepts pets.

Federal law does not criminalize panhandling or begging.

You should only be screening based on credit report, criminal background, income and previous landlord references.

Then there are the ones who call me and are eager to schedule a tour, but as soon as I ask them about their income, credit or criminal history, all of a sudden they mention they have an eviction, a felony, or make less than the rent.

Anyone using FinRET for background, credit and criminal checks? 

With as many tools as there are now for background/credit/criminal checks and rent payment systems, it's really not bad.