John Ogdon once sight-read Brahms' Second Piano Concerto in a concert. However, although he had never played it before, he had heard it previously.
I find it is easier to read some composers than others (some just make more immediate sense). Things that make reading difficult are very fast passages, lots of accidentals, infrequently encountered keys, large leaps and unfamiliarity with the genre.
What about pieces that are kinesthetically weird like bach?