I've had 2 sets of Chromes on my bass and both have had a significant amount of some kind of dark residue that I noticed when I scrubbed them with alcohol. I'm guessing that this residue is from some sort of polishing compound that D'Addario uses to finish polish the strings. After I alcohol scrub the strings they become more shiny and noticeably smoother. I wonder if your strings might become acceptably smoother under sweaty conditions if you were to scrub yours as I do to mine.