What even worse is the cultures where you throw another type of hello/goodbye gesture into the mix.

Take Montreal, Canada: Half of the population there says goodbye via two air kisses, half hug, then you got the formal handshakes into the mix. Nobody announces what they're doing when they go in, so it's not uncommon to get the hug + two air kisses, which feels a little sexual to me.

To add to the complexity, you have people of different cultures in the city. Arab men for example kiss on the cheek but don't kiss the women. So you need to size a person's culture, sex + the level of the relationship up whenever saying hello or goodbye to people.