I disagree - but negative reviews certainly almost always are.
Pictures of health code violations and stories of health code violations usually raise some red flags (especially if recent). Those are too easy to fake.
The most useful ones are when they go through exactly what they thought was right/wrong with the food (and a pattern emerges across the pictures and multiple reviews about different dishes).
If the restaurant is a 3.1, then yeah, try to find a different place - there IS hair in the food, the cockroaches are real and the waitress DID stick the hotdog up the you know what.