Good question. I like it so I'm going to reply to it.
I think being a fan can be split onto 3 definative areas:
1) FAN - An ardent follower
2) FANATIC - Excessive enthusiasm for and intense devotion to a cause or idea
3) SYCOPHANT - A person who tries to please someone in order to gain a personal advantage
As described by
www.dictionary.com
I'm definately No.1 and being a fan to me means admiring what someone says or does but not necessarily having to agree with everything they say or do.
Pud:o]