I'm not convinced that 2008 will be a good predictor of how the next recession will affect the mystery shopping industry. Consider:Technology has allowed for more and more purchase to be made online, as opposed to at brick-and-mortar stores. Retailers are able to get customers to do surveys on their smart phones. Etc.
When recessions hit, companies start to lose money. Each company reacts differently, but nearly all have to find ways to reduce expenditures. Many will find their mystery shopping programs something they can put on hold, preferring to care for their employees. Others will simply reduce their programs - monthly, instead of weekly visits, etc. Others will substitute what we do for online surveys and the like. Very few, if any, will expand their mystery shop programs. At the same time, more folks will be looking to make money on the side as they will be between jobs or working for less than what they make during strong economic times.
In other words, I believe we will have more folks competing for fewer mystery shopping jobs. Shoppers who are well-established with schedulers will likely continue to get more than their share of the work while newer folks will find it harder to break in to the industry. Folks who are used to getting hefty bonuses for shops in Timbuktu will find that other shoppers are willing to the same drive for less.
Expect fewer jobs and lower pay.
Hard work builds character and homework is good for your soul.