Usually it becomes trolling when people finally get tired of arguing with someone in that position and wants to end it, but at the same time don't want to appear as though they're giving up. They label it as trolling and usually it gets stopped.
SomethingAmazing said:
Intentionally taking the opposing side on a debate for the sole purpose of playing Devil's Advocate follows what trolling is verbatim.
Playing Devil's Advocate is not posting intentional fallacies solely to get a rise out of others. Let me try to paint you a picture here. We're in a debate between the three major gaming platforms and I've decided to play Devil's Advocate for PS3, despite being a hardcore PC fan.
This would be acceptable for someone in my position:
The PS3 can do all sorts of things besides game, and it's easy for people to hook up and use. You don't need to be into computers to have fun with it.
Now, if instead I wanted to troll the discussion, I could drop something like this:
Did that help clear it up?