Lust: Good or Bad?

This Five for Ten series has us writing on Lust for the next installment. I am struggling with this one. Is it good or bad?

• Seedy, underground nightclubs for actions too dirty to reveal in the light
• Married men with their secretaries violating the sanctity of their vows
  
• Happy couples, neighbors - friends that go horribly wrong in a momentary lapse of judgment

But, there's also a way to flip it; to turn it around to be something better, something good.

• Lust for life - that spirit that keeps people going long after some would give up and wither away
• Lust between legitimate lovers - the most intimate connection
• Lust for learning - devouring, consuming all one can for knowledge sake

For me, I think the concept of lust is really negative. Even if I can cite some positives, it just feels dirty and wrong. I don't know, maybe I'm just a prude. What do you think?