I usually ignore the star ratings completely and read the text of a few reviews. This isn't a personal policy, just something I've done unconsciously. The stars don't tell me anything useful.

(Reading the reviews is by no means a good system—it's time consuming, the reviews are poorly written, and I never know what to believe. But if I ignored everything I'd feel blind.)

Before I started ignoring the ratings, I absolutely bought products with 3 star reviews, since my view was that "3 stars" means "it's fine".

And you know what? They were. I never really noticed a huge quality difference between things rated 3 stars and things rated 5. And, since I started ignoring the ratings, I've purchased things with 1 and 2 star ratings on Amazon (that were well-reviewed in other places). Those have generally been as good as the 4 and 5 star things as well -- and a couple of them were actually excellent, deserving of 5 stars rather than 2.