Most companies that hire for search engine evaluation have multiple projects available to work on, so the exact work you do might vary. However, search engine evaluation in the traditional sense involves analyzing queries that regular people like you and me might type into Google or Bing search and then determining the best possible results to match up to that query so that users have the best experience possible using a search engine.
What’s the catch? None, really. Cash back apps act as affiliates for many online merchants, which means that whenever you make a purchase through one of the apps, they get a small commission — but then, they give you a portion of that commission as “cash back”. For example, if I buy a pair of Nike shoes through the Ebates app (or website) and spend $75, Ebates may get a $10 commission but then they’ll pass $7 back to me. It’s basically a way to get sale prices on stuff that isn’t on sale!