Debbie, Here is a link
to a picture from this site
(not knitting related per se, click on the "non-piping link" ), which shows what the different kool aid/flavor aid flavors look like when used to dye a creamy yarn and a darker brow/greyish yarn. Might be helpful.
I wonder what would happen if we knitted/felted an off-white swatch, and then bleached it after it was felted?
It would probablly be different for each yarn...