People watching is fun, whether it be with comedic company or just alone, it's something everyone has done at least once. It is also something which people would prefer not have done to them. Everybody loves getting a good laugh out of seeing a fashion disaster strut down the street as if they own it; on the other hand, nobody likes being stared at and being laughed it when their turn comes to step out of the house in something worn by a solid candidate for "What Not to Wear."
Hypocrisy is the best policy though, isn't it?
Instead of pointing out the flaws within those who are fashion-challenged, try not to laugh or ridicule them... doing that does not bring you any benefit nor does it bring the person into awareness of the "do's" and "dont's" of wearing appealing apparel.
Instead of directly ridiculing people, try to first make a joke about something which you are wearing, or what everyone else around is wearing... establish ethos with the person. THEN it is okay to mention something about what they are wearing and suggesting that whatever it is, is a faux-pas and NEEDS to go. After you see the shock on their face of "wow... I look horrible!" or "what did this person just say to me?!", before they actually have the time to say anything, give a solution for their problem.
For example:
Me: I dress awful all the time dude, but some people take the prize.
Friend: Oh really? Like who?
Me: Well, you're kind of wearing a faux-pas altogether...
Friend:....
Me: Let's go shopping sometime soon? Lunch date and then shopping? It'll be fun.
Friend: Sure, let's do it!
-This method works with any insult, just insult yourself first to establish comfort and credibility and then proceed to present the person with the bitter truth. Lastly, give a simple, easy solution and take it as an opportunity to help people who need it.-
