Exaggerated: Every single thing the troll posts is something like this. He may also use Sock Puppets.
Downplayed: The troll posts a disgusting pic but it is very small or linked with a proper warning.
The topic is "Most Disgusting Picture I've Ever Seen".
The topic or discussion or community is one in support of racism or homophobia or some other form of bigotry, and the pics aren't necessarily "disgusting" except to the bigots involved, though they may still be NSFW or offensive, though that is the point. For example, someone spamming a community of Heteronormative Crusaders with gay porn and yaoi.
The troll posts links and imagery relevant to the topic(s) at hand that aren't disturbing, disgusting, or incendiary.
The troll posts links to pictures of puppies and kittens disguised as links to disgusting images and videos in a thread about the topic "Most Disgusting Thing On The Internet".
Subverted: The troll posts a link that is relevant to what's being discussed.
Double Subverted: The link or image is still very disgusting/shocking/NSFW.
Parodied: The troll posts G-rated LOLCats and people react like he's posted links to Brazilian scat porn.
Zig Zagged: The troll posts offensive and shocking pictures, and is warned by a mod rather than immediately banned. The troll then backs off a bit, becomes a Lurker, and then starts posting pics again, but just on the borderline of breaking the rules.
Averted: The troll doesn't post on the forum.
Enforced: The topic is "Most Disgusting Thing I've Ever Seen Online"
Lampshaded: "Ugh, dude! Don't post crap like that!"
Invoked: Pics from a Shock Site or similarly disgusting images begin to appear on a website or social media community.
The troll is using the pics to draw attention to his or her new Shock Site.
The troll is using the pics to point out hypocrisy or to achieve some other goal.
The troll decides he's better than that and decides to just start a Flame War.
The mods and admins chastise the troll, then take down his posts and ban him from the site.
Discussed: "Anyone remember when someone hacked the board to redirect to Goatse?"
Deconstructed: The mods and admins quickly ban the troll and remove his posts or lock the topics.
Reconstructed: The troll learns his lesson, creates a new account, and follows the netiquette.