I came across someone who specialize in teen glamour (i.e. girls under 18 dressed in lingerie, bikini etc..) I am wondering what others think of it? Would you let you daughter pose in those pictures? Would you let you son look at those websites?
A site that "specializes in teen glamour (i.e. girls under 18 dressed in lingerie, bikini etc..)" is morally questionable at the least. I would not let my daughter pose for that photographer or give permission (because it would require my permission) for her pictures to appear on his website.
This does not mean a clothing catalog might not have a picture of a teenager in a bikini or in underwear--that can be done without an appeal to prurient interest (yes, there is a small percentage of men who are aroused by the sight of a the nipples of a four-year-old of either gender, but we aren't talking about those guys).
The whole point of "glamour" is not just to illustrate a pretty face, the ultimate point of glamour is an appeal to prurient interest. That appeal isn't so much a matter of dress or even pose, but a matter of the suggestion or implication of sexual availability.
When you're implying sexual availability using someone your society has made taboo to sexual availability, then you're over the edge.