Being both a vamp, and a darker fae, I can understand the darker glamour perfectly. I'd say it's not so much drawing people to OUR pain, more so drawing them to what seems to be mysterious, shadowy, unobtainable and enigmatic. Add that in with vampiric compulsion (influence through energy) and you've got a toxic cocktail of manipulation. I've found that it's very easy to draw someone to me and "bleed them dry" of whatever it is I want, so to speak. I've experienced "bright" glamour once, and the fae was so cheerful I sort of wanted to punch her in the face. xD Bright glamour, I agree, lights up a room even in somber times, and I can very much understand how those who are hurting would be drawn to it. I would think that dark glamour more easily draws those that are a little too confident. They think that they can reach what is just beyond that shadow, and it easily devastates when they can't. Like you said though, bright glamour can leave some extremely depressed when they leave it's presence. Both are very dangerous in their own right, but can be very useful.
I've also found dark glamour to be useful in confrontations, for the sole purpose of appearing dangerous, or threatening to the person wishing harm. Well, glamour CAN weave illusions.