Ditto! I once came across some Twitter and YouTube accounts where teenage boys were trading keys from Steam. Illegal, of course.
Apparently, these cases of cracking happen a lot.
I must say, I did use some sites with keys about 10 years ago when I had lost some registration codes of software I had bought. I'm not particularly proud of that, but in this case it was defensible, I guess.
In all other cases I would stay away from it.
Rich