Depends what you view as crap or junk, really.
Lots of people think sugar and butter are the devil incarnate and would prefer sweeteners and low fat.
Those people are barking, IMO.
Saying that, I figured that sugar was pretty much empty calories for both DSs in the first year of their lives, so they won't have it. From one, I got a bit less strict with it.
From 6m to 12m, they're growing ridiculously fast and their cells are getting all sorts of messages about how to behave for the rest of their lives (this is SO scientific, this way of thinking...!) - basically, I want to make sure my children have a good start, foodwise.
DS1 hasn't got a sweet tooth now, and he can take or leave "treat" food - he likes chips, he likes crisps (Organix Goodies ones ). He is a party ring refuser though - sweet cakes and biscuits do nothing for him.
DS2 likes cucumber and oranges best of all.
I don't take them to McDonald's because DS1's very favourite out and about food is an M&S sandwich.
I try very hard not to let them have things with transfat, artificial colourings and sweeteners in. I think that the "everything in moderation" lot should have a look at the effects of some of these things. I don't restrict food, I do restrict this non-food muck.