Two possibilities I can think of. First, if they are in-ear headphones (typically have some foam or soft plastic sleeve that looks like it could fit in to your ear) then they are actually designed to be inserted in to your ears. Improper insertion can result in bad sound transmission and very poor sound quality, particularly on the lower ends. It would sound very tinny like you seem to be describing. Make sure they are inserted all the way, that your ear canals are not blocked by ear wax and that ear wax has not clogged the sound hole in the earphone itself. It can sometimes feel a little weird the first time you put in in-ears but if you have the plug properly sized, it should become comfortable once you get used to it.
It could also just be the fact that it is SkullCandy. They are similar to Beats audio... ie, they are more concerned about marketing and image than about actual sound quality. It does sound unlikely to be the problem though as such companies tend to prefer to be low quality in the sense of having overpowering bass at the expense of washed out and muddy everything else. That said, in-ears don't have the best bass response in general because of their small size. Until you move up in to the several hundred dollar pairs from reputable companies like Shure and Senheisser the bass will not compete with even fairly cheap (read $5) over the ear headphones and it won't compete with good over the ear headphones until at least the $530 or so point with the Shure SE535s being the cheapest real decent bass response in-ears that I know of.
Disclaimer: I own a pair of SE535s and have not followed the in-ear market super close since I got them, so it's possible a decent set may be out cheaper now, but I have not heard of anything with solid bass response other than them that is cheaper.
