It isn't whether a track is "dark" or not. I think the problem with techno at the moment is that people have forgotton about the essence of good techno tracks, there has to be something at the core of it which makes it work for the head and the dancefloor.
I think a lot of the perceived "darker" end of the spectrum has become too wrapped up in the atmospherics and structure of a techno track, kind of overlooking the dancefloor, and the central necessary nucleus of a good techno track. Dark stuff done well is excellent, but the genre has become a bit flooded.
At the moment I prefer tracks that are dirtier and rawer, more minimally arranged, as long as they have something to drive the music.