lexipixel - 2:22 am on Jun 11, 2011 (gmt 0)
It does happen. It's evolutionary. Let's say you joined Facebok when you were 14 years old, and became a fan of several "gothic novel" figures, a pop princess or two, and your favorite lunch snack.
A few years later, you tastes change and you cull the old and reinvent yourself.
Another effect is the "just too many" problem -- you can't be a fan of everything or your online persona appears vague.
And, since it's "social networking", some things just go out of favor with your social network and the peer pressure to un-fan a page occurs.
People's taste (especially younger people's) in politics, music, food, travel, fashion and other trendy topics are subject to the same fate.