I don't when I see it? But I would have to see it in most of the reported games I'm viewing to believe it to be a possibility.
If someone is really hacking you shouldn't report it to the Tribunal anyway. You should make a support ticket with pictures, a LoL Replay, or just the time and date of the game for them to review.
If I see "This guy was hacking" from the enemy report, that says to me they're angry more likely than not. I've also seen people mistake the "Graves Smokescreen" FPS killer, and teamfight stutters be accused as "hacks."
I might take "this guy was hacking" from an allied team more seriously - especially if the "hacker's" score is something silly. But still, can't see it in Tribunal and a support ticket is more effective in finding hackers and exploit abusers.
Riot gives out special "do not pass go, do not collect $200" permas to hackers they catch.