Please don't smell my baby.

This is pretty common. I don't know it they are really smelling the baby or this is just how they react when they first see them (like people in the U.S. making baby noises). I've witnessed it a thousands times but never bothered asking. To answer your question you just have to tell them. Have your wife say it's bad luck to sniff, wake, or whatever it is you don't want them to do. Just have her blame it on you. For me, it works every time..

P.S. You're lucky it's not a boy or you'd have to deal with them pinching it's privates, seriously.

They don't see mixed babies very often, so they go ga-ga, goo-goo over them.

Hi,

This is the way here to kiss.
Your baby might be cute.
Just explain your wife that you don't like your baby to be kissed especially while she's sleeping.

Enjoy your fatherhood.
BR,

It's common everywhere to love babies but waking up and make them cry isn't really good 
I know someone ask politely to touch or pick up the babies.

My baby has come in contact with many Vietnamese people and I've never seen or heard of this happening. Maybe it's because I live in Phu My Hung and the Vietnamese there are more aware that this is not acceptable behavior - I don't know. But we also take her all around the city as well, and all VN people who see her are very polite. The wait staff in restaurants love to play with her, standing behind us making silly faces to make her laugh. But we've never had anyone get too close or inappropriately touch her.