You can observe this same multi-factor effect in restaurant or product reviews. When a restaurant serves one customer unsatisfactorily or a product is delivere

You can observe this same multi-factor effect in restaurant or product reviews. When a restaurant serves one customer unsatisfactorily or a product is delivered in poor condition, the rating suffers substantially. This rating no longer represents the quality of the thing itself but also the individual's experience. The same is true with a cook's experience preparing a recipe. Depending on the reviewer's bias, a recipe rating might describe circumstance and culinary skill better than the quality of the instructions. As other folks here have mentioned, there's also the issue of average reviewers being not-so-great at representing their true opinions with linear rating systems, but that's a whole other topic.