Not so much now, but when I was younger, I would get a lot of playful micky taking of my love for the genre, but then people would approach me later with the comment, "actually, I quite like... (insert sci-fi series here)".
My best friend says he's read about five books in his life. He is the brightest person I know.
I don't find people dismissive of the genre at all. I meet many people that don't like science fiction, but I think it's lost the image of being just for kids.