A lot depends on how much leash you're comfortable handing over.  

In addition to a renters insurance policy and vaccination records from their vet, we limit the size of the dog. we also add to our property rules that the dog must always be on a leash, they pick-up the dog poop and the dog must not disturb the other residents if this is a multi-family complex. 

In my area leashes are not optional and all dogs must remain in full control of the owner at all times. 

(I want it to be tenant-sturdy). 

Letting your dog run around your front yard off a leash is illegal.

If a person/tenant wants to leave a lease nor a leash will hold them.

Hopefully, if that situation arises, the notice results in attitude correction and the lease can continue uninterrupted.Having said that, if the eviction is 5 years ago, I'd probably accept the couple - but let them know I'll be keeping them on a short leash.

For rentals, you want it to be sturdy.

Here is your 3631 Elm Ave: https://www.google.com/maps/place/3632+Elm+Ave,+Ba...Charles Village is full of large sturdy 3-4 story brick townhouses, many of which have been converted to small multiunits that house Hopkins students. 

Without having gone inside, I can tell that some sturdy laminate flooring, a new coat of paint, and slightly upgraded appliances (with perhaps a cabinet upgrade here and there) would probably bring the units up to standard.