Is it just not my worry what their income is since the voucher covers the rent, or is my concern that if they only have about $950/month then they won’t properly be able to maintain their pets and their standard of living valid?

If you make this investment, not only are you going to lose all your money, you're gonna get dandruff, your dog is gonna die and your daughter is gonna run off with some biker dude!" 

But many travel med profs travel as a couple, with their families, with a pet(s), and they want or need extra space to spread out.

I pay all utilities and make them pet friendly.  

A few thoughts...One I had something similar with a neighbor who had my number and texted me after I moved out of my unit and moved a tenant in to complain about my tenant and his dogs.

Move to duplexes and you learn you need to pick compatible tenants to avoid becoming a mediator in disputes about noise, pets and parking.   

The illegal process is to show up and chase him off the property, secure it again, and use methods to prevent entry again (dogs, security system, signs, armed person sleeping on the property, etc.).

Check for unauthorized occupants and pets?

They want to look you in the eye and tell you about their kids, dogs and how the weather is.

I do have some pet peeves but I have learned to work around most of them.