A great salesman can also be sociopathic. We are all salesmen to some extent, so this isn't to denigrate the profession or the ability to read people and use it for personal gain.
I suppose the difference lies in whether what one is selling tends towards symbiosis or exploitation.
I couldn't understand these things until I interned in a software outsourcing company. Empathy started to make a lot more sense. Employees felt like slaves, which clearly had an impact on their lives and productivity of the company.
In my understanding, empathy is pretty much a skill to emulate the other person's thinking. There's a discussion about Kolmogorov Complexity, which says to emulate an already complex system you need an even more complex system, which means a bigger brain. Of course human minds are not that simple, but I think this is onto something.
In addition to smartness, you'd probably need a patience and some serenity to react (or not react) to the situation accordingly.
I thought empathy had more to do with the part of your brain that is able to pick up on facial expressions, body language, and spoken tone ("social queues") to make inferences that are not otherwise explicit. Mild autism suppresses this part of the brain, meaning you could have someone who is very "smart" but lacks empathy and social skills.
And of course it can be learned, which is part of the treatment for mild autism, but many (most?) normal people are able to tap into something much more instinctive.
You must talk to people before you can understand them.
You mean, that _bad_.
Great salesmen are always in a good mood, never negative, never criticize, never go off on random tangents and know what the other person is going to say even before they say it. They can tell immediately how a target market will react to anything in a product or offering. It's like they can easily put themselves in the other person's mindset to understand their gut emotional reaction to things. I only dream of being that good. The best I can do is to clumsily emulate it, but it requires concentration to pay attention to everything, it's like speaking a foreign language but never quite thinking in it.