You can also request a security deposit for extra peace of mind. 

A couple of thoughts that might help.I recast a loan at a point where I had paid enough extra to allow recast (I think it was $5k over).

I want to upgrade my house up a notch in the couple years and get a couple little extras like that.  

It's easy to obtain, costs very little, and doesn't require extra, on-going effort to maintain.

If they have nowhere to go or don't know how to find a next place, and no relatives who are helping them, you will be the only person that goes the extra step to help (even with advice) which means you will get the sale at a better price and help someone.

Luckily they’re being truthful.

The tenants have paid and if someone is thinking about moving out then an extra surcharge that hits if they aren't out in time for us to turn the place for a lucrative AirBNB short term rental can help massage the move out timing.That said with MTR we do not have the cleaning costs that eat up a lot of STR gross, and its lower hassle in some ways.  

Earning an extra 3% on $2k that you’re likely holding for less than a year.

To further answer your question: the truth of is subto legal is “it depends” - now is it criminal - most likely no - but could it be illegal yes.

However, I definitely recommend pictures any time a guest left damage or extra cleaning that will result in additional charges.