I have worried about this a lot, but basically now try to get inspiration and take example from webs that I consider highly readable. I also developed a set of internal rules; for instance, my maximum "black" is #333 (#333333) and my minimum "white" is #eee (#EEEEEE). Anything going further than these to the middle should have a real reason and not just because it's prettier.

Edit: #333 over a #eee (worst-case scenario with my guideliness) gives a 10.9:1 ratio, while #333 over #fff gives a 12.6:1 ratio, both totally acceptable. So I am not sure how the author concludes that #333 is not good enough and we should use #000;

Why should the people who is doing it right and pleasant change it because few others are using ridiculous colors as in the examples? It's like saying you shouldn't eat any sugar at all because many people is fat when you are perfectly healthy.