It would be against the TOS if the "content is illegal, promotes illegal activity or infringes on the legal rights of other" That is the question you have to ask. It depends on the rules at each individual download site. If they are warez sites, I wouldn't consider doing it. Google does look at any sites that raise a red flag to determine if a violation has occurred.
Google has been on a vendetta to disable accounts with crappy web sites or borderline violations of their TOSs.
A friend of mine just had his account closed permanently closed (yes, they told him that he can never open it again) simply for having web pages in a site with affiliate links that no longer operated. He never updated the eBay affiliate links when the program was moved from CJ. I didn't believe him until he sent me the communication with Google. Even though he has fixed the site and pleads "mea culpa" in his messages with G, they still refuse to re-open his account.
"It's inexcusable for scientists to torture animals; let them make their experiments on journalists and politicians." -Henrik Ibsen