Some states require landlords to look at the total income of the tenants, like CA, but others allow landlords to require that each adult can pay the entire rent on their own (3X the rent, etc.).So, it just depends.  

I'm renting a 3 bdrm-1 and 1/2 bath rowhome to a tenant family of four adults who are habitually late with their rent payment each month.

I have always been interested in real estate as my adult life has spanned the 80s through today and i have seen a lot of appreciation over the years.  

adults=1&children=... 

For example, my ad will state whether we accept pets, that we want provide income around 3x the rent, and that every adult must pass a credit/criminal screening.

We went into the room where they do the auction, and didn't look as out of place as I had originally thought we would - I had attended an auction as research before, but it was a regular foreclosure auction, and there were a bunch of lawyers dressed like what I assume actual adults are supposed to dress like - ties, pants suits, etc.

Two able-bodied adults who make life choices that result in eviction, but the landlord should feel sorry for them? 

Quote from @Jerome Wiley: Can the landlord ask a perspective tenant how many adults will reside at the rental property?

This is a response from the Section 8 tenant 68-year-old female high credit score of over 700 never late on a payment in my life on a mortgage or rent I'm on the other side I cannot get a decent place to live because I have a hood voucher only because of becoming disabled and Senior

I am not an experienced REI, however I work with a large number of young adults executing duties that could have serious consequences in the military.I would seek out an employee who could teach you the mistakes you would make before you make them.