Well, the IRS says cash gifting with the expectation of return is illegal. That is FEDERAL law. The FBI has cracked down on many rings and even more at the state level.
Illegal activity goes until it is stopped... yes. That doesn't mean it's promotion should be allowed. Marijuana ads are banned, so should any other illegal activity.
My concern is for Clixsense users that expect ads to be vetted at the very least for their legality. It is civic duty to watch out for those who may be scammed and even prosecuted in criminal court. As a respected member of the WWW and the leading PTC board,
has an obligation to watch out for its users.
Submitting a ticket to remove one ad won't solve the problem. Guidelines need to be amended and made routine to screen out all such adverts. It doesn't take any extra effort as all ads are screened anyway. It simply needs to be added to the list.
It isn't illegal for Clixsense to run such ads, but it can be liable in a civil lawsuit. Craig's List is paying millions over similar issues.