Lee Cosmetic Highlight Filter
I would say that it is a waste of money to buy any type of color adding filter for a digital camera. Manipulating an image in post processing can give you many more options.
Simply increasing the WB a tiny bit, for instance, will make human skin look better because it adds some red and deemphasizes the yellow color that is really there. Beyond that there are many, many options in post processing.
|Common Flashwing by digimania|
from canon dslr
|The Marilyn impersonator by Lee8282|
from Blowing in the Wind (Nature)