Sportsmanship

There is something that has been bugging me for over a year now, but it wasn't until a few days ago i was able to put it into words. I warn you now, what I have to say might offend you. So you may want to stop reading now.
So here goes... Some of you know that I come from a family who is very dedicated to a sports team. I also married into a family that has very strong dedication to a sports team. Growing up I was taught to cheer for my favorite team no matter what, win or lose. I can remember by dad jumping up off the couch and pacing around the living room because he was nervous or upset about what was going on in the game. Something I don't remember is my dad bad mouthing the other team. Yes there was the occasional dislike of a player but that's about it.
So what I am confused about is, when did cheering for your team mean to bad mouth the other team? I just feel like, if you feel the need to put down another team it can come across as a lack of confidence in the team you are cheering for. Yes there can be some playful banter between friends who know their bounds and it's all in good fun. But when you go to a game and get cursed at the entire game because you are wearing the other teams jersey? whats that about? But then there are the smaller things like calling them Cowgirls. That might seem small, but whats the point. Isn't it already understood that if you are cheering for one team you will not be cheering for the other?
I am jealous of people who can just sit back and enjoy the game and who don't care who wins and loses. I am not one of those people and I am not married to one either. There are some times when I would love to write something as my status that would annoy people cheering for another team, but I don't want to be like that. I want to be proud of my team win or lose. If they win hooray for them. if they lose then that's to bad. That is one thing that I respect my husband for. This past baseball season his team had a rough time battling injuries and what not, but he still stood by them and cheered win or lose. Living out in no mans land, we don't get a lot of his teams games so he would watch them online with our very VERY slow internet.
I know that there are so many of you who are very dedicated to their teams and I applaud that. My challenge for you is the next time you are going to say something about another team are you being a bad sportsman?