Troll review happens all the time. Why do we now make threads about it all of a sudden?

Same here.

Oh MGSV.

Yes, or when it goes against what is believed to general consensus. 

When the content of the review is complaining about irrelevant things on an imprudent way and you feel like they are trying to get content in order to lower the score. Also, when the publication has gotten a bad reputation or is well known that it is biased against something and the review is evidently lower than the rest without solid arguments. I find a perfect example on a reviewer called "Quarter to three".

The second it praises something it just previously criticised in another game.

"too much crafting, even to fire your bow you have to craft, its tedious"

then

"You can't fire your bow without first being sure you have enough to craft some more arrows. Its a beautiful mechanic that gives the game more depth"

Yes, some reviewers are that contradictory.

Only if you look at it at face value. Execution of said mechanic is important. ICO is one giant escort mission, but its done so well that we ALL overlook a mechanic we know we'd be complaining about somewhere else.

When the critique is stupid such as the infamous "too much water" review for ORAS

Not bad to me, but low enough to cause outrage.

Instead of joining the bandwagon, i thought it'd be worth seeing what's considered a troll review to the pissed off gamers

Yeah, Mario Kart definitely doesn't deserve a 7.9, but I have seen IGN give even worse games higher scores.