If it is unprovoked swearing and hostility, definitely screenshot it and send it to an admin/mod in a report. There's rping and using words, then there's general harassment that shouldn't be tolerated.
I tend to walk about seeing what everyone is up to, but wont join unless invited (or if I do, and they say they are in a serious rp, I respectfully apologize and leave them to do it). If it's a public map, you have a right to be there, but your right can't trample over others by trolling them if they politely ask to be left alone.
Honestly, I really suggest to people if they want a rp with no interruptions whatsoever that they make or request a map for it, or go to a map that isn't populated as often, or an area quite out of the way on a public one. Nothing frustrates me more than when a group decides to plop in front of a main portal and claim it as their territory...like lolwhut?
I really wish people on the game would be more respectful to each other. We have decorum on here, and it'd be great if it could trickle over there.