i don't know. I'm wearing this pair for years, and it still doesn't need to be washed.
what color are they now?!
ive only seen ppl wash it in sink with soap (or bleach) and then let them sit in a bucket soaked for a bit. after that ull just have to untangle the strings
i figure that cleaners would do a good job, (if money's not the issue) though i never tried it.
but personally i dont bother washing them, i just get a new pair every 6 months (b4 pesach, b4 RH)