I hate sarcasm

Really? I'd have never guessed.

I have the opposite problem. I don't always want to take the sledgehammer approach and sometimes want to be subtle but sarcastic at the same time. People often don't get it, particularly people who don't have a culture of sarcasm.

Maybe it's the tone of your voice. That can change any meaning of what is being said.

If so many people think this about you, perhaps you should examine the way you are communicating and change.

I hate when people are sarcastic over the internet. That after get angry since no one understand they are being sarcastic. "Oh, I love sports" and "Oh I love sports"(Sarcastic) can be taken either way. Some phrases have an already negative connotation so its easy to read those. However its ignorant to believe this is going to work with every single sentence. I think maybe we should have an internet icon we can add to mean sarcasm. We have smileys and all this other stuff we really need one for sarcasm. I also hate when people switch between sarcastic and non-sarcastic when nothing they have said has a negative connotation so is not coming off as SARCASTIC.

It could be your faciel expressions and things

Yes, I think it's completely normal to get mad when people misunderstand you. But as BfingIToucher said, maybe you should check your communication skills.