I'm pretty sure Scott can for his vocals, because I saw him looking at a music sheet during Too Cool Queenie on the Thank You DVD.
he's the only one who was classically trained at his instrument. dean and robert self-taught themselves and weiland doesnt play an instrument though he was in advanced choir back in his high school days
Scott did write the music to Tumble in the Rough.
Its possible that Scott was just looking at the lyrics.
You dont need to read music to write songs, or play an instrument