I also wash my machingers and they come out nice and clean....no problems whatsoever. I put them in the dryer and haven't had a problem with them losing their rubberized fingertips. I just recently bought an extra pair as I have been using the same ones for years (bought them when they first came out) just to keep them on hand if mine finally gave out.
Have to agree with SuzanneG...it is amazing how dirty they get. I have often thought what on earth do I do to get them so dirty.