Is there a business in your town, which you are 100% sure is a front?

There is a solar tanning parlor of sorts in a street close to us. I might just live in a bubble where noone would ever go to one of those parlors, but it seems to be open pretty late, and it feels like there are often some unsavoury people going in/coming out. It's become a running joke that it's a front, to be honest don't have a clue but I wouldn't surprise me.