I've done a couple but like Flash mentioned, their shops involved "laying out a whole bunch of money on stuff" you have to return at another time--or not! In the two that I did, I had to go to 5 specific store departments and purchase a minimum of $50 worth of stuff. My biggest issue is, I ended up liking all the things I purchased that I ended up with unplanned expenses. On the second shop I did, I promised myself not to even bother going through the store's things; I was just going to grab the first thing I saw and run to the cashier. Unfortunately, I'm a born shopper and couldn't just go through with a grab and go as planned.
I did get paid pretty quickly, minus $3 because I forgot to complete a direct deposit agreement.