I can play 4 different instruments (piano - grade 4, Flute - grade 6, drums & steel pans) so can read music very well. Reading music is just like learning a script for a play. But knowing how to read music really isnt everything when playing guitar. Its all chords etc... Ive always wanted to play it but could never get the hang of it, my brother has tried many, many times to teach me to no avail.
so I dont think its got anything to do with being musical, although a sense of music and rhythm obviously help.