Use some discernment in the tenants' character. 

The house has a lot of character and I even leased it to a movie company for 2 months for them to film in!

If the other tenants and/or landlord feels that the additional traffic to or signs posted on/in the unit is out of character with the neighborhood than that would be addressed with the city granting the license.Resourceful tenant following the letter and spirit of the law = generally a great tenant to have especially when the next downturn hits.Ask for proof of the license, insurance, permits.

You've stumbled into one of my people's major character flaws...once we walk away from something, we file it away as "done" in our brains.  

True to her character and evidence of my lack of skills in dealing with PITA tenants ... 

It's just that some vital aspect of our character has changed that values show over substance & appearing bigger than ourselves.

These are cheap fixes that give it a little character. 

Although if it does bother you, you can check their references to have a better idea of their character. 

But, if they want a smaller and more unique experience as their home (with a bit more character), then your place may be ideal.

Remember in the Bugs Bunny cartoons when a character realized Bugs was playing him as a sucker?