I can tell you that for me, personally, it led to a full time job.
My first shop was a pizza mutilation shop. A friend of mine told me that she would get $5 if she referred someone who did one, so I did it. It's amazing that I stayed in the business! My second shop was a nice steak dinner for two, so that got me more interested. I had a full time career in marketing at the time. My husband and I worked for the same company, and started picking up mystery shops that would give us free lunches and odds and ends on the way home from work. The fees started adding up and helped us save for a downpayment on a house.
I heard that a gold workshop was coming to a town a few hours away, and decided that it sure wouldn't hurt anything to do it. The cost is also a tax deduction. I did see more offers once I went gold - and I can tell you now from "the other side" that many offers do get posted to gold shoppers before they are released to the whole shopper population.
A couple of years after attending the workshop, I got an email from KSS (that went to gold shoppers) saying they were looking for schedulers and I applied for the job. Now I work full time from home as a scheduler. It has been a really positive influence on my family life, since I'm home with my daughters every day after school, as opposed to rushing home after work to get them from daycare, slap something on the table and get their baths before bedtime.
So, that's my testimonial. Gold was great for me.