For a mainstream example, take Fast X. It's an objectively stupid movie with a great audience score - because it's exactly what it says on the tin! Nobody is confused about what they're watching. Nobody thinks they're going to get terrific drama or romance or suspense. They're going to get the 9th sequel to a comedy action movie about dudes driving cars.
My favourite way of judging movie quality is checking what kind of movie goers hate it and why.
-Pretentious watchers hating on summer blockbuster movies
-Political things and review bombs
About your specific example Steam comes to mind, they have a great review timeline feature that allows to filter out review bombs.