Why do my earphones fade out within 6 months?

I have an iPod nano 4, and within 4-8 months of purchase, (usually around 6, though) my earphones usually either fade out, or go out in the right speaker. I’ve gone through 4 pairs this way so far, cleaned the jack multiple times, cut down on the use of my earphones, and I don’t even use that loud of a volume. I remember a similar issue with my nano 2, so is this my iPod’s doing? Or are the earphones just cheap? Will this happen to my new wired Beats headphones if I use them with my iPod?