What does pink ribbon symbolize, and how does it relate to faith?

The most
common answer to your question is that the pink hair ribbons symboize Faith's innocence and when
she loses it so that Brown finds them on the ground it signifies her loss of innocence.  But I
wonder if the symbolism is as simple as that.  Pink hair ribbons would have been frowned upon if
allowed at all in the austere of Puritan New England.  Most women, married or unmarried would
have covered their hair with a cap.  So here goes my explanation which may or may not be
right.

I believe that one of the theme's of Hawthorne's story is that there is
sin in all of us no matter how pious we are on the outside.  This is what Brown realizes in his
trip (or dream) to visit the devil.  Even though these people have claimed salvation, Satan
still rules their flesh.  Thus the pink ribbons rather than symbolizing purity (they would have
been white if that were the case), symbolize the mixture of good and evil (with white for good
and the red of Satan for evil) in all of us, including Faith. They, I think, also symbolized the
uncertainty of Brown's faith so that when he found them on the ground they represented his loss
of faith, and Faith's apparent abandoment of the good half of her for the pure evil of Satan. 
The fact that the ribbons are in Faith's hair upon his return would signify that she rejected
Satan's total controll and signify Brown's still mixed faith.