Here is the thing, you give of an "E-scent" that trolls pick up. It's in the way you type and the way you bite their hook. You just have to remember a troll is essentially a bot. They don't have an opinion ("you're gay" means the same as 101101010001011 because they're just a bot and who cares) and they don't have feelings. Trolls are so much like bots that they actually run on sort of a script most of the time. You can spot them usually because they use the same misspellings and almost the exact same tactics. It's like they have a training center or something. Sometimes if they're prolific enough you can copy and paste what they said in Google and find it posted all over other forums. They just autonomously go around trying to make people mad because they get beat up in middle school and have to take out their frustration by making everybody hate and mistrust each other. I'm pretty sure they would all grow out of it by high school or even adulthood if they're developmentally challenged.
How to respond to them? Simple, you can just ignore their bla blas because all it is, is a bla bla about bla bla anyway.
Otherwise if you feel you should respond, follow the basic guidelines of these examples but the possibilities are limitless and if you tinker with enough of them you can actually manipulate them. I have still yet to find a use for them.
If you think somebody else might be tricked by them in a public setting then just sound the alarm by playing the where's troll-o game and reply with: "Ooh I spotted the troll! Troll failed again
" Note you never address or even acknowledge that they ever said anything other than "bla bla bla, I'm a troll bla bla" This is a two fold response because they know you're on to them and you didn't give them a response that triggers them to continue their routine. This can send them into defensive assault mode (where they fly off the handle humorously) or they may disconnect. After that no response is needed but if you feel you must raise their blood pressure, just remember to not pay much attention and reply to what you imagine them saying, not what they actually copy/pasted in the forum.
Another thing you can do if they paste a long rant they don't actually believe in or PM you is to just reply with the command "cool story, bro". All trolls are programmed to cease probing or psych-exploiting in much the same way the old analog telephone switchboards would disconnect on a 2600khz tone. Flip switch, light comes on. Very rarely do they have an error from this and continue their routine. Debugging the troll is not worth it so just ignore or repeat your previous message.
If you get good at dealing with them you can trick them into thinking you're a victim or "lol cow"(possibly "lul cow" I think) and get them to put in a lot of effort while you just sit back on your end giving half assed responses that didn't take more than 10 seconds to think of and type without ever reading what they said. They all say the same things after all so if you read one, you read em all.
Hehe, youtube can be fun for that. I even found out the personal account of one (remember they like to re-use text even in their personal info section and google can help you find their other accounts) when I was bored and got him to waste his time making video responses and rage like no other when I impostor-ed as him and contacted his friends and later exploited youtube and a macro to send thousands of mass emails to him
Save the fun stuff for youtube though because it's a wasteland and we don't need that kind of pollution here.
Edit: If they start their own thread as some of them do, just drop this in there and it sometimes is enough to snuff them silently for a while.