It’s an internet shopping network with thousands of products from hundreds of companies. Many times when you see ads on a website, many of these are done through a shopping network like linkshare. The web owner joins the shopping network, places some code on their website, and the ads are loaded each time someone views their page.
Not sure about the mystery shopper opportunity, but it is probably just being offered through the linkshare network.
The email says they are looking for someone to report via surveys and perform evaluation exercises on behalf of GUESTLINK®.
???