"Surely there must be some way for advertisers to tell Google 'do not put our adverts on content provided by the following: ..."
Unless you are keeping very quiet about a massive break-through in Artificial Intelligence, the three dots at the end of your question can only be a list of specific providers.
It is an insoluble problem. Expecting a machine to be able to say "This is offensive, but that isn't." is absurd in a world where real human beings chosen for their good judgement have been able to argue in court for centuries over the exact definition of offensive and whether particular material is offensive.
Biting the hand that feeds IT
