The ones that tell you to pay them before you get a job: my friend did that against my advice, and never got any money from it. Basically, for your money, they send you a list of companies that you have to contact yourself and see (a) do you do mystery shopping? (b) will you hire me? (c) ok, well then who do I have to go through to get this occassional minimal paying job since you won't hire me directly?
There was a company in Baton Rouge that I used that was legitimate, but YOU DID NOT PAY THEM, THEY PAID YOU. It was only for JC Penny though, and I think I got $10/visit. It was when I was younger, and I'd swing by on the way home from work when they asked me to, and get my $10 in the mail after submitting the information online which I considered gas money.....back when $10 could be considered gas money. But to tell the truth, it was occassional, and the form was so detailed and had to be filled out just right...and the amount of time I took to do the shopping at all the different sections, and then get online and do it correctly (had to be complete and done right or you don't get paid)...only a teenager with time on their hands would find that worthwhile. A part time job somewhere (anywhere) would be more lucrative.