Smell like a baby... Well well, I had a bunch of them and the smell is...
1) Vomit! You know, the milk in excess, the burping that leave traces. Like a old bottle of milk behind the window under the sun... A bad cheese!
2) Poo poo. Since they only drink mother milk, the poo poo is not horrible, it is sometimes like fresh bred or cereals... But once you introduce the first food (artificial milk, fruits, real cereals, ...) it start to be more smelly. And the day you add meat... no comments.
3) Sudden diarhea... No poo poo pocket in the diaper, just the onesie that becomes colored by this pseudo-liquid everywhere. Thanks to special collars to remove the onesie from the bottom!!!
4) Stuffies horror show... Chewed, used for everything... Can be very smelly
5) Skin issues... Can smell oignons or even worst (very common and not dangerous).
6) Toys... Some toys can have all the above smell in one !
7) .....
So when someone says, sleep like a baby or smell like a baby, for me it's a sarcastic way to say "horrible".
BUT:
When they are freshly bathed, changed, loved... The smell of a baby is absolutely wonderful. My favorite was when they were very small, still in a kangaroo like device on my belly, I absolutely loved the smell of their heads and the neck. I don't know if it was pheromons or anything else but it was my abolute favorite.
Small note: except the point above, babys and kids don't smell bad at all. The bad smell starts with hormones (pre-teens). Start with foot, then arms, then everything (because they start to hate to cleanup)... And suddenly the first boy/girl-friend appear and they start to smell perfume