Agreed, but my point was that those that are lowest rated will likely have the worst cultures, and so would be *most likely* to retaliate. A company with a good culture would in theory be more likely to take any constructive feedback on board.
Although it probably gets you further than the opposite extreme where everyone disagrees all the time.
Personally having such info (critical reviews on previous employers) for a candidate, would be close to already having their answer for "Tell me about a time you had a challenge/problem/conflict at work" type of interview questions.