Here is a link in regards to dyed anemones etc
http://www.wetwebmedia.com/dyedcorals.htm
I tried to find a link that i had on Reef central a couple years back as i was tempted to buy one as we'll.
And Anemones can indeed be a very pale yellow/light brown but never the vibrant yellow that those nems are.
Most lfs have no idea that they are indeed dyed and many nems can and have lived. They just lose the colour over time.Or sadly perish from the dye.
It is of course once again the suppliers dyeing them to look great so they will sell.
Just my opinion of course...lol