I was thinking about this topic and, normally, I'm not the type to say "never"....but on this one series, I think I can be safe in saying I won't be reading the 50 Shades series. One, I don't read erotica (not that I'm a prude, but I've tried and find I normally skip over the sexy parts to get back to the story) and, two, I've heard from people I respect that it's just not very well written.
Another series I don't plan on reading is an older one... WEB Griffin's books. I know people love him, but I'm not all that interested in military fiction and these (from what I've seen) are huge...so, yeah, not planning on reading those.
And, let's not forget The Twilight series...I tried with that, honest I did... made it through the first book but was so not interested in reading the others. Nor seeing the movies.
And, there you have it.. my very limited list of books I'm not planning on reading. What about you?