Avoid, avoid, avoid! I had the same experience as Wade...as soon as I got out of my car, a skeezy guy approached me and pointed to a scratch on my windshield. He said he could fix it for free on my insurance. I politely said no. He responded by saying that if I didn't get it fixed, it was likely that the next time I drove over a bump, that my entire windshield would shatter, onto my face. Right. Get away from me, creep.
Worse, the cleaners are awful. They don't dry your windows completely so you have water spots right away. They spray awful fragrance in your car even when you ask them not to. And they use damp towels on the dashboard and wheel that leave dirty streaks.
Save yourself a lot of time of annoyance and go someplace else.