well that depends on the trend. Personally, i find many celebrities to be stuck up and annoying, so why listen to them?
A trend or fad among certain age groups are the same thing. i went from transformers to pogs to pokemon to nintendo to XBox and im still not done.
it seems everyone follows trends, but you are correct, many make no sense and do not deserve to be cool. For instance, the fact that it's cool to dress like a gangstah rapper and treat others like crap while muttering jibberish that the people who speak it barely understand it simply seems like nonsense to me, and it seems to be what "all the kids are doing" which makes me stay away.
its like "Hey! You wanna shoot yourself in the testicles? It's so cool! You have to do it to be cool."