One of the few social advantages of being a chess player is that people assume you must be intelligent. Chess players, of course, know this is simply not true. I've known plenty of players who could barely string two words together and were so dumb they probably needed an instruction manual to go to the toilet.
Me? Well, I'm a mathematics graduate, an accountant, and have an IQ of around 130. So I'm not exactly Einstein (pictured) but I can tie my own shoelaces. However, as a chess player I'm utterly mediocre. Chess requires a very specific set of knowledge and skills, so there is no guarantee that being smart will mean you are a budding Kasparov.
Of course, the opposite also applies. You don't have to be smart to play good chess. This is the big secret that the non-chess paying world doesn't know. You are all sworn to secrecy - I mean it! If word ever gets out it will be the end of one of the few perks we chess players have. So if someone asks you if chess players are smart, just answer in the affirmative and misquote Descartes, "I think, therefore I play chess".