I'm starting to note that mellow unfussy happy babies are the product of mellow unfussy happy parents. This baby has a drool-soaked pink top - her parents were unfussy enough not to bother to change her out of it for photos. And I didn't mind either - the drool made the color a deeper shade of pink, which was better for photos.
It probably also helped that the photo session was on the (naturally lit with lovely ambient light) home patio - though it was her first foray onto the patio, the baby was sitting in a familiar high chair, and provided with an array of familiar toys.