"Fair Weather Fan" is usually intended as a slight or insult, but by definition it is neither.  It means that you support a team in "Fair Weather", but withdraw that support when they are boring or not playing well.  Everyone's Fandom is different. 

Personally, I will always watch and cheer and be excited about every little success.  That doesn't mean that I don't know my team is lousy and that I don't wish changes and improvements, but that is just the brand of my fandom. 

Feel free to enjoy your fandom in what ever way suits you.