This article is interesting because, unlike a lot of customer service "research", it's based on some hard data.

Does smiling help or hinder sales?

And it arrives at conclusions that are, to many, surprising.

To summarise the article:-

Some social scientists devised an experiment to try and test the effect of happy, smiling customer service in a real world scenario. And what the effect was on the sale compared with a sad or neutral facial expression.

I won't spoil the plot - you read it.

Smiling is just one of several elements of non-verbal body language. It is also the one that is most easily detected as being fake or genuine.

The most well known scientist to have done research into the "technology" of smiling was called Guillaume Duchenne and he identified two types of smile. One which includes raiding the cheeks and smiling around the eyes, the other without. 

More recently the expression "Pan Am", or BOTOX smile has been coined to describe a totally fake smile. Having worked in the airline business for a while I think I know where this came from!

My interest comes from what I have observed about customer service in Japan. What they call "Omotenashi" service. Generally rated to be the best in the world.  My observation is that it is not a culture that uses or forces a big smile in service situations. I have never felt myself on the receiving end of an inauthentic facial expression.

The wordless component of their customer service authenticity appears to come from their attention to detail and consistent attentiveness throughout the process, from initial greeting to polite goodbye.

In Japan, it is not about the smile - it's about the attentiveness. And that is where the all important authenticity comes from.