I will say that male budgies, do make the better pets. You will see about they're beak, some budgies are cream to brown in colour, they are females generally, and males are blue to purple. Baby budgies dont stink in general, a nice clean cut looking bird, with bright eyes, and no build up of anything around the eyes or beak general area is starting to look like a great bird. Also, there shouldn't be any kind of build up of any diarrhoea underneath the bird either. Some humans can get sick on occasion from a sick bird like this, but pretty rare.
To tell if a budgie is a baby (although you cant in a yellow one)....The bars on the head go right down to the beak, where the colour of the sex of the bird is able to be told. If the bird is say a blue one, and it has like a white cap on its head and the bars are further back, this means the bird has gone through some "molting" periods and is actually not a "baby budgie" as such. I have 6 budgies myself, and they're great as pets