Anecdotally the worst McDonalds Burger I had was with a cold slice of cheese at the Berlin Main Station, while the Döner there was always above par.
When your falafelshop is in the neighborhood you can't be scamming people because you'll quickly become abandoned.
And I also do a quick sort by newest. If all the newest reviews are tourists, I know to steer clear. Tourists will give a convenience store egg sandwich 6 stars out of five. They'll write a full-on essay about the fine experience they had at a restaurant and saying it's obvious the chef put lots of care into the meal, not realizing it's a local chain restaurant that just pops things in the microwave. Then they'll take off 2 stars at a good place because the chef couldn't make them a gluten-free, rice-free, beef-free, soybean-free chicken burger (also, they have deadly poultry allergies so they can only eat chicken substitutes). I also see loads of these types of reviews.
I recently had some really bad experiences with some fast food places in my corner of the world, at a train station as well.
They all had 4.9 stars but lots of 1 star reviews matching my experience. But also tons and tons of eerily similar 5 star reviews with a generic photo of the counter (no faces, no food) and a random name and glowing review of who "served" them. Which is impossible at those places.