There are some scams out there - generally, if they ask you to pay them for their service - look elsewhere. I worked in hospitality for close to 30 years, and we paid folks to critique our hotels and restaurants. They would stay, eat, and drink for free, and also get paid a fee on top of that as well.
In my experience, you can't really make a living on 'shops', but you can certainly get some extra pocket change.