obscenity has never been protected. it is not considered "speech" under the auspices of the 1st amendment. therefore, it has never been protected. as for what constitutes obscenity, it is defined as one supreme court justice put it, "i know it when i see it." swear words are speech. there are numerous cases where the words fuck, shit, ass, etc. have all been upheld when in the context of a communication of a thought, such as "fuck draft", see cohen v. california. but just saying fuck, shit, etc. without the communication of an idea is not speech under the 1st amendment and is not protected.

so, if you flame, send nasty emails to people such as the editor of a magazine (like, say mixxzine) saying that they are fucking cocksucking morons and that their editing choices are as fucking bright as sticking a broken light bulb up their ass, it would be protected speech under the 1st amendment since you are communicating an idea. end of story.