Once soy is heated, it does undergo some significant chemical changes that degrade all the bad stuff ~ besides, I never drink soy oil.
Actually, corn oil has some problems too, but soy and rape (AKA canola) are the worst. Butter is totally safe in the quantities that most people consume. (If you ate it by the fistfull, you might eventually clog your liver and gallbladder)
Maybe not knowingly. It's in everything from soft ice cream, tofu, "nutrional" drinks, and fake "meats". Hydroginated soy bean oil is in practically all processed foods which claim to be 'good' for you. That's why you should always read the labels.