If you push the everyone has different tastes argument to its logical conclusion, than nothing is inherently better than anything else, and there is no such thing as an objectively superior audio product. To a degree this is true, and we see it all the time here; for example, people are often split over Grado and Sennheiser, or the HD-650 and the K701, but all of these are excellent products, with no real consensus on superiority.
Now that being said, I think we can agree that some things are just inherently better for the majority of the population. Someone might like a Toyota Carola better than a Lexus GS, but overwhelming general consensus in going to be that the Lexus is the superior automobile, regardless of the tastes of a few outliers.
Skullcandy doesn't make bad products, but they are pushed more for aesthetics than for sound. They have cornered a unique cultural market, one that is highly concerned about the coolness factor of their headphones, and slightly less concerned about their sound. These people aren't wasting they're money, they're spending it on something else: image. Nothing screams loser like walking around with a pair of HD-650's, these bad boys are confined to the comfort of my room. Skullcandy has made their products "cool" to be seen with, which is more than Grado, AKG, or Sennheiser can say.
All of us (most of us) here on Head-fi think Skullcandy sucks because we're really only concerned about audio quality, not aesthetics. This is an audiophile community. That also means we tend to have a collective taste that is different (not necessarily superior) to the general public, who often prefers certain parts of their music to be more accentuated (usually the bass), whereas we generally prefer a more flat response. Even within our own community there are some outliers, but I think the collective Head-fi consensus would be that Skullcandy is not a good headphone when based on its audio merits alone.