I think we need to define Christ's statement:
Matthew 5:28
But I say unto you, That whosoever looketh on a woman to lust after her hath committed adultery with her already in his heart.
I don't think this is the same as looking at a woman with interest. For example, if a young man looks at a picture of a model with interest it's not lust, it's normal human interest. If a young girl imagines what it would be like to be with her science teacher she has a crush on or a boy she likes it's not lust it's normal human interest. Most who are governed by the Spirit would be terrified and never act if the opportunity arose. Lust in my opinion is something far more serious. Lust, for example, is when a man looks upon a specific woman with intent to actually pursue and act on gratifying his sexual desires. For example, if a man is looking at a woman sitting at a bar and begins to actually plot and determine as to how to hook up with her, that's lust.
I think we must be careful because we condemn far too many with blanket notions of condemning normal human interest.