Then I will have to reread it ... if I can find the books. But yes Cade is not a good example cause of all the anger inside him. As for Anakin's case, I need to find it and double check.
But basically I think this comes down to if you invoke a force power flowing WITH the white current of the force flow itself, of you forceably bend it against its flow by sheer brute domination. Grated, many of the force powers are quite neutral in that it requires only a smell detour for the force even when it comes to a DS wielder, while some techniques have an obvious twist and domination of the force flow. Things like Force Rage is almost definitely DS, but the rest is somewhat grey.
I mean if ther is DS technique to heal and revive and LS techniques to cause destruction, then the line is pretty blurr indeed.