Junk food is what it says: Junk! How can this be good for health? Yes, it taste good because it has taste enhancer and it looks good because it has artificial colour in it. It is offered with images that suggest that you are modern and so on. It is easy to prepare: Called 'Fast food' and so people like it, without thinking about the consequences.
Baby food already contains sugar and other substances that make the organism addicted: The future consumer is secure! Indeed: Never there have been so many obese children and their sickness is already programmed. Clients for the 'health industry' making business with peoples disease. Then making them addicted to medication for the rest of their life!
And you ask if it is good or bad?! Not even in moderated quantities it is good! Avoid it totally! Try to get organically grown vegetable and fruits, drink clean water and stay away from alcohol, tobacco and all kind of drugs. You are taking in enough poison from breathing and touching all kind of plastics and being in contact with chemicals that are every where present. So it is necessary to do regularly a cleansing of your body, if not even though with healthy food you will get sick in its time.
That's just the physical level and even more important is that you accumulating a lot of stress, that will bring your system out of balance and will end in sickness...
Read my hubs about it.