USA tyers are very late to the CDC game. That includes the shops and online retailers, resulting in very uneven quality CDC, some of it just junk despite well known names on the package. Trouthunter is an outfit that knows CDC and the bulk package is a decent deal.
For flies like CDC and Elk, or patterns where you can strip and bunch the CDC, you don't need great feathers, but for mayfly wings like those in the photos by wbranch, you need full, nicely filled out feathers.
I use them some just to give a different look to jaded trout. That is, when a standard hackle or parachute, etc. doesn't work, a CDC may.
For slimed CDC, I rinse vigourously and dry with a spongecloth followed by vigorous false casting. That only goes so far, but then that's true for any pattern after a while.