Have you ever had someone stick their hand out in such a way that you weren’t sure wether they expected a handshake or a high-5, (well… low-5 actually)? It’s all the more difficult to tell when it’s over the shoulder. And coming from a person who would seem comfortable with either.
And I didn’t really think of any of these things until afterwards.
So, yes, I am a paranoid freak, why do you ask?
In some businesses and positions, it would be easy to say that you should always default to the handshake, as the least likely to be offensive. But… you know… not really. Because building up a casual relationship with your clients is incredibly important.