I don't think there is anything wrong with junk food occasionaly. At least once a week the kids have fish fingers and chips for dinner (we buy Crumbed Whiting instead of FF) and once a month they get Maccas as a treat.

I beleive that as long as you have everything in moderation then it's fine. As long as the kids eat all their veggies with their dinner I don't mind if they have a few biscuits/chips for morning tea.