First off, having the ferret spayed (which is necessary for her health anyway)
will cut down drastically on the musky smell. Secondly, you're bathing the
ferret too often. That in itself can cause a stronger smell. Try using
Johnson's Baby Shampoo since it works as well or better than any of the
"special" ferret shampoos and is also a lot less expensive. Bath the ferret at
most once every 2 weeks although once a month is better. Mine seem to get to a
point after three days where the muskiness doesn't get any stronger. Cleaning
the litter box(s) daily and changing the ferret's bedding at least once per
week will also help.
[Posted in FML issue 0848]