We're all geeks here, so we can be honest: We've all got the show that we know we should watch, but don't. The hole in our otherwise-impenetrable nerd repertoire. I'll show you mine if you show me yours.
Some things just ... slip by. There isn't enough time in the day. You didn't know it'd be good when it started. It ran for too long to jump in now, or go back and catch up. You hate that actor and his stupid face. Those are all perfectly valid reasons not to watch a TV show, and no one'll hold it against you. But it sits there, nagging at you, as you see a fanbase rise out of the geek mists, embracing that which you chose to ignore. And you start to wonder if you haven't made a huge scheduling mistake.
For me, my biggest blind spot is Supernatural. I'm sure it's good; people I trust, and whose taste I trust, have told me so. But I watched the pilot episode a few years ago and just didn't dig it. It felt a bit like Buffy lite, without even the pretty girls to look at. Allegedly it's developed into a show with everything I like: strong leads, fast cars, a dense mythology and bad-ass angels.
Will I ever watch it? I couldn't say—perhaps a lengthy-but-not-serious illness will sideline me for a couple of months, in a cabin in the woods, with nothing but Supernatural sets and scotch to keep me company.
But enough about me: What's in your sci-fi TV blind spot?