For the record, I rarely leave reviews. When I do, though, it's only for the exceptionally bad or the exceptionally good.
It's hard for a product or service to exceed its expected value by more than a fraction or small multiple, while it's easy to cause misery well in excess of a dozen or even a hundred times the expected value. I believe that's more a reflection of it being easier to destroy vs create rather than a reflection of psychology. Combine this distribution with a heuristic to only report deviations from expectation in excess of a minimum threshold and the "average review score" will reliably undershoot the actual quality.
That's only a problem if you want to interpret the average review score as an absolute measure of quality, though, and I don't think anyone really does. Most of us are more interested in communicating and informing our decision processes than in passing moral judgement, and if our goal is to optimize communication then we should expect negative reviews to dominate the discussion because they're inherently capable of more meaningful excursions from the mean.
I agree with your overall point: it would be fantastically useful to be able to contextualize reviews against reviewer psychology. That way I could ignore both shouting from negative-nellys and forced positivity from those who feel compelled to balance the universe :-)
In reality, however, it seems that positive reviews tend to dominate. Using Google Maps reviews as my barometer, I hardly ever see any place rated less than 4.5 stars. So, I tend to think to myself "4.5-5 stars: might be good. 4 stars: probably okay. Less than 4: maybe steer clear."
Though, in practice I disregard reviews, take a plunge, and then decide on my own. Often I find myself in conflict with the average majority opinion.
It's interesting that your main criteria is how you feel you were treated, though. Discussed in the article:
"Restaurant reviews in which people sound traumatized by perceived injustice don’t tend to comment much on the food — it’s usually the perception of being treated rudely or uncaringly that seems to have pushed people into processing by writing out their feelings in a public forum."
I honestly feel the same about poor service. I'm usually accommodating and understanding, but I'm no monk. Of course there are times when I feel either the poor food or poor service merit some mention.
Most of the time, however, I think "they're human, going through human things. No big deal."
If I have a specific complaint for a place close to my heart, like a coffee shop or restaurant or local shop, I’ll talk to the manager, privately and calmly, and be on my way.
Doesn't mean you have to, just means that it'd be more helpful to others if you write "it actually is what it claims to be" reviews.
Do you consider them equally attractive?