Government created special unit to defend their positions and reputation in internet. All resources, after gaining some popularity and reputation are added on watch list, and flooded with cremlinbots after. Their basic tactics are - simple insults with no reason, changing discuss point, confuse your mind, trick your arguments and dodge everything. Their main attack point is your emotions.
How can you track them down?
Unfortunately, you need some experience from facing them. But main points are: they are highly aggressive, mostly stupid, they using cliches(propaganda manual) widely. it can be effective only against inexperienced opponents. On practice it can looks like: Russia's great because: your are loser personally, news you brought is lie, i work at X place, earn shits of monies, other countries is worse because of taxes, shootouts, gay madness, and so on. Of course, all that is lie, aiming at your emotions, not solid and logical brain.

here's articles, if your need more.
https://en.wikipedia.org/wiki/50_Cent_Party
Chinese example.
http://www.nytimes.com/2015/06/07/magazine/the-agency.html
http://www.theguardian.com/world/2015/apr/02/putin-kremlin-inside-russian-troll-house
https://en.wikipedia.org/wiki/Trolls_from_Olgino
Articles from trusted sources.