There's a reason many don't consider programming a wholly exact science. There's a shade of art to it, like in every other type of writing.
One can try to follow every set of guidelines one finds but there are always cases where such guidelines become hindrances or they might just not fit completely with other guidelines. The more "legible" one's code becomes, the more differences with others' code one notices, making "what's entirely clean code" a subjective question.
And, more than guidelines, I feel one learns better from reading generally accepted code; and what's important is that the code is maintainable, if it fits the problem at hand, it makes sense and the average programmer could get up to speed with minimal pain, it's good to go.