When I worked in the motor trade you'd get reviewed on absolutely everything. Some of the things people would mark you down for were incredible; even had one that read "Brilliant service, couldn't fault it" and scored four stars. Meant I lost out on a bonus for it as it's five stars or nothing.
There was a story on 'Angry People in Local Newspapers' a couple of years back about someone who won an award from TripAdvisor for most reviews posted in a year - something like 700 or so. Maybe more. Curiosity led me to looking up that profile and it would appear that their daily schedule consisted of get up, walk to the local McDonalds for a coffee, get lunch from Greggs, walk by somewhere on the way home and occasionally go out for a 'Spoons tea. Almost every single one of those five stars, she even reviewed a stand containing tourist attraction leaflets at a train station.
I'll always leave a positive review for independent restaurants, cafes and the like on the usual sites as it's a good way to show appreciation; one place I helped run got massive attention from good reviews and it's nice to repay the favour. Reviewing a coffee from McDonalds (five stars every single time does literally nothing to help local restauranteurs and hospitality businesses, in fact it just hides them in amongst the multi national chains. It's tacky as hell.