Questions about mystery shopping?

We have all seen those ads where you send 29.99 for a list of mystery shopping companies and you can make thousands a week. We have also seen the ones in our local pennysaver, the ones where they send a large check supposedly on behalf of a mystery shopping company. I would like to open this discussion so you can ask any question you have ever had about the mystery shopping business. I have been doing it for ten years, I have written a book on it and I am the President of the Independent Mystery Shopper's Coalition. So, I have lots of experience and I would like to answer your questions.