Sometimes it is a good thing -- like Vitamin D being added to milk. That has been done for decades and addressed a serious shortfall in diet. Breakfast cereals can easily have vitamins added which is usually a good thing -- unless kids take a multivitamin they are probably not getting everything they should have.
But I have to agree with you -- I have seen chocolates with the label "Fat Free" on them. Chocolate is _naturally_ fat free but the problem is that has a shitload of sugar! And then KFC that likes to say "No Trans Fat" but it is still swimming in grease~ it may not have trans fat but that sure as hell does not make it healthy!