So how does the beauty of a pure man or boy manifest itself? I would suggest for starters that it is very unlike any Hollywood characters. Such male characters are often proud, arrogant, violent or aggressive, even if they are shown with a 'soft side'. A pure man would have nothing but a soft side - although some sternness may come through where discipline or disapproval of bad actions is needed. My guess is that a pure man's nature would not be attractive to many women, as these women may be seeking men who demonstrate material power or they may be attracted to some men's over-confidence, which in many men has its roots in pride. A pure man or boy may in fact be more like the somewhat shy seeming, or meek boy that confident and mean-spirited girls like to try and put down, and less confident ones, or at least softer-hearted ones, may find attractive as they enjoy their company due to their lack of airs and the absence of a competitive nature.
Thus a pure boy, I imagine, is humble. In this sense I like C. S Lewis's description of a Christian - as if after meeting one you might most remember how much more interested in you he was rather than himself. A pure boy definitely does not view girls or women with any sense of sexual desire, but just a pure spiritual love which engenders in him a gentle, patient and forebearing manner. He does not seek to prove himself better or tougher or cleverer than anyone else, and he is not interested in such one-upmanship. He would be very self-confident, however, this would not be evident from any vain posturing, but only from his quietly confident ways. His confidence would draw from the fact that his nature is pleasing to God, if not to worldy people. The pure boy seeks to be helpful where he can and would do no harm to others, nor take pleasure in anyone's misfortune or weaknesses. He would not take advantage of anyone, but he would speak out if he felt something was wrong or in defence of others - if their cause was just and they needed it. However, such a speaking out would not be an aggresive challenge, but more of a earnest admonition.
Thus I feel that such a boy or man would have a rather admirable character, from a spiritual perspective, if not from a worldy one - which tends to favour overtly powerful, and perhaps overbearing characters. If you are interesting in being more like this, then that requires training the heart in this direction, which in turn requires careful introspection and identification of any behaviours or feelings that are inconsistent with what you want to achieve. Careful guarding and correction of your thoughts, and much prayer - and no doubt much fasting (from old, bad behaviours and pleasures) should lead one a fair way down this path reasonably quickly.