They've been loading pirated software full of trojans since file sharing became popular, it didn't work so well over MIRC, but when napster first came around, the whole thing became a booming business. Many of them were software companies trying to get personal information to sue with, a lot of others were dumb kids being bored. Either way, it's a prevalent practice, which is why you always check the comments when you download a torrent
I don't remember it ever being this bad though. Well Kaza sucked ass but that's why everyone used e-mule.
And I might be wrong but wasn't Napster mp3 only? or did that change before they where shut down? and I never used MIRC for file sharing. Did use Usenet though and that was very safe (relatively speaking of course) thanks to strong peer review... Unless you where in some asshole end of alt.binaries.thefuckareyoudoinghere
Today though, it's just out of control. At least that's what It looks like to me. Never remember it this bad.
And reading comments doesn't help much.
<poster 1> My virus scan told me the keygen is a trojan.
<poster 2> Oh don't worry, keygens do change things on your computer so they can be falsely detected as viruses
<poster 3> It's true
<poster 1> Shit I just got a virus from this.
<poster 4> Stop lying you RIAA shill.
...reads the typical comment log on pirate bay.
About the only "safe" torrents out there come from forums. And even then you shouldn't download anything from someone with low post counts.