So what is the difference between a troll and someone who always criticizes the Nats ? We have plenty of the latter on WNFF.
I think it depends on how you define a troll. Below is what wikipedia has to say, so you know it must be true.
In Internet slang, a troll (/ˈtroʊl/, /ˈtrɒl/) is a person who sows discord on the Internet by starting arguments or upsetting people, by posting inflammatory,[1] extraneous, or off-topic messages in an online community (such as a newsgroup, forum, chat room, or blog) with the deliberate intent of provoking readers into an emotional response[2] or of otherwise disrupting normal on-topic discussion.[3]
Application of the term troll is subjective. Some readers may characterize a post as trolling, while others may regard the same post as a legitimate contribution to the discussion, even if controversial. Like any pejorative term, it can be used as an ad hominem attack, suggesting a negative motivation.