A good example of this I have come across lately is the book, "Where there is no doctor". It sounds like a health book for people who don't have quick access to medical attention and it sort of is. But the two main mantas in the book is the promotion of communism and abortion.
He couldn't shut up about it. It was in every chapter. It ruined what could have been a very useful book by making it mostly unreadable.
The left sticks it's messages everywhere where they don't belong. Check out childrens' shows (cartoons and otherwise) on weekend mornings. Unreal socialist/enviroweenie/one-worlder propaganda.