Canny Edge Question

A quick question; why does canny edge detection work better on grayscale images? It is stated everywhere that it works only for grayscale though i tried it for color images and it works on them too, only it detects too many false edges. What is the reason for that, it works on intensity and i believe intensity stays the same whether it is a color image or grayscale?

How are you representing the colour space? Try performing edge detection in HSV instead of RGB (if that's applicable advice. Otherwise, act appropriately.)