It takes some experience to realize that a place graded 7.x probably has serious issues.
The opposite situation can also occur. At my university, entrance scholarships were decided a few years ago based on students' aggregate score across 25ish dimensions (I can't remember the exact number) where students were each rated 1-4. Consequently a student who was absolutely exceptional in one area would be beaten out by a student who was marginally above average in all the other areas. I suggested that rather than scoring 1-4 the scores should be 1/2/5/25 instead.
I generally sample the lowest rating written reviews, to check if people are complaining about real stuff, or are just confused. For instance, if a hotel doesn't have a bar, some of the negative reviews will usually be about how the hotel doesn't have a bar; these can be safely ignored as having been written by idiots (it is not like the hotel is hiding the fact that it doesn't have a bar).
Occasionally some of the positive reviews are similarly baffling. Was recently booking a hotel in Berlin in January, and the top review's main positive comment about the hotel was that it had heating. Well, yeah, I mean, you'd hope so. I can only assume that the reviewer was a visitor from the 19th century.