I have same problem, and they also just stop working after a while. I've tried expensive ones that are supposed to be sweat-proof, but although they last longer, those died too. Eventually, I just learned to buy several sets of cheap ones when they're on sale on Amazon, and just plan to swap them out every six months or so when they crap out. Consider it a badge of honor that you're spending lots of time running.

The same thing happens to me sometimes - I think it's sweat that gets into the earbuds, as they usually get a bit damp. If I wait a day or two between using them, they're usually fine (though the same thing may happen again).

Best earbuds ever http://www.amazon.com/MEElectronics-Sport-Fi-Noise-Isolating-In-Ear-Headphones/dp/B0038W0K2K/ref=sr_1_1?ie=UTF8&qid=1381016147&sr=8-1&keywords=meelectronics

I've noticed that, after mile 2 or so of my runs, my earbuds sound quality really begins to tank. My left earbud becomes virtually useless and my right earbud has minimal sound. I've had this now with two separate earbud sets. Is it the sweat from my head/hairs that's impacting the quality, maybe with the wiring being shorted? Is it the fluid buildup and pressure in my head that's impacting my hearing? Strange...