Yeah, but "Sith Lightning" can be good in the games, and in the EU they just call it "electric justice" or some other such crap. It really doesn't make any sense.
All we know from the movies is that only two guys use lightning and it's bad. Oh wait, but Yoda used it [Insert angry fanboy saying that Yoda didn't "really" use lighting, he only reflected back, being the good non-violent fighter that he supposedly is]
There's so much confusion and lack of consistency in the Star Wars universe now. It's really there because Lucas decided to let his EU team do what they wanted, then he just decided to bulldoze it for the prequels, and instead of restarting the EU (which I think they should do now) he left them to try to make it all "fit" somehow. It's a big mess.