Smart is a weird word and I don't know if I would describe me as that.
I rather consider myself as rational/intellectual. I might not know a lot of things, but I feel like the way I think is somewhat uncommon when compared to the general population. Emotions don't cloud my judgement as much, and I seem to have this ability to take few steps back and observe things from afar. Because of this I'm a really mixed bag when it comes to my views on current affairs, and by knowing my stance on few issues doesn't really help you to figure out what I think about the rest. I can usually also be honest to myself about facts even when it's inconvenient for me.
I'm the kind of person who you ask a simple question from, and you get a lecture in return, because I'm physically unable to give overly simplified answers to complex, nuanced questions which is basically all of them.
I think this one suits me most without sounding like I'm blowing my own trumpet.
I would include that my common sense is brutally lacking. I would also say that I'm happy with short answers but I'm emotionally stunted enough to consider everything without too much bias.