If they're doing things the right way, they should. I work on the other end of things as an advertiser. Our contracts with networks clearly spell out the kinds of sites we can be on, the kinds of other ads that they will and won't run, etc., because it's no good to us to be affiliated with a bad actor advertising network. We also do a ton of diligence on networks to make sure they're above board, and monitoring after we sign with them to make sure they're adhering to the contracts.

What SHOULD happen is that IB should have contracts with only reputable networks that they've thoroughly vetted, and those contracts should explicitly lay out the kinds of ads that can be served up, with an out if the network serves up bad traffic. The minute people report bad ads (as noted in the many, many pages of the bad-ad related thread), IB should be going back to those networks to either have them correct the issue, or they should be discontinuing business with them.

Unfortunately, IB has clearly made a decision that they're just going to go with whatever ad networks give them the most money, without particularly caring about the repercussions to its users or the site. The result is that the site is now being marked as a malicious domain. Perhaps if people can't access the site, that will hit them in the pocketbook and make them think about only doing business with more reputable ad networks.