Mystery Shopping
Mystery Shop Companies are legitimate. There is even a Mystery Shopping Association, it is at
http://www.mysteryshop.org/. It is legitimate as are the companies that are listed on this site.
I have been doing Mystery Shopping for over 6 years. It is most definitely a legitimate occupation. It is also perfect for RVers.
Go to the site above. Check out the Association and the Companies. Judge for yourself.
Remember, though, that you should NEVER need to pay a fee to Mystery Shop. While you may need to pay for your meals or items, you will be reimbursed for your puchases plus paid a fee for the job (called a "shop"). You sign up with individual companies and look for and accept shops from them. Most people who Mystery Shop work for more than one company. You can't usually make much working for just one company.
There are also different types of shops. Most are anonymous, where the store being evaluated does not know that they are being evaluated (yes, this IS perfectly legal), but there are other kinds of shops where you restock a display or make sure that there are current brochures where they are supposed to be.
While there are a lot of scams, there are for practically everything. Check it out for yourselves. The Association above is made up of Companies that abide by certain standards and so do the Shoppers who deal with them. There are certifications for Shoppers also, although they are not required. When you work for them you are not an employee, you are an independent contractor. Most of the companies pay on a regular schedule and most of them now use Direct Deposit or PayPal.