Hi
I Mystery Shopped with a company called MRC operating out of Dublin.
I had a great time with them.
Basically, job was going into branches of large chain stores, critiquing the tidiness, displays, time to get served, testing salepersons' knowledge of products, hanging around the items which are a shoplifters dream (razors apparently) testing how quickly a staff member will begin to watch you (this last one always bothered me). In any cases where I had to buy an item (admittedly with my own money) it was just to keep it for an hour or so and then return it for a refund to test the companies' returns policy.
The most I got paid, if memory serves me correctly as my last Shop was in 2004, was €50 per visit. I was paid mileage, but this was negligible. The other two jobs I did were paid at €25 and €15.
Where I live there were several branches of each of the three chain stores I was asked to visit, so I did each one in rotation and found that I was called back regularly to revisit. The jobs themselves were quite quick, the main thing was to read the instructions and make notes of the things you had to look for. On one job I had to record the time of every single task, ie time entering shop, time to order product at counter, time to pay, time to wait for product to be presented, time leaving.
In some of the visits the instructions were quite detailed, so I had to have little hints written on my palm to remind myself of everything. Sometimes, the job required a visit on two consecutive days. At times, I felt that I was quite obviously a Mystery Shopper, but with practice I think I got quite good at browsing and observing.
I think if you prepare yourself well for your visits you will be able to complete the questionnaires with ease.