I quote from a website I saw "Avoid keys that put instruments playing sharps alongside instruments playing flats. In this syllabus we talk of F# and Gb as the same note. This is true for tempered instruments like the piano. For instruments in the violin and brass families where the note is felt for, F# and Gb are subtly different. Is the last comment correct, and I assume also valid for double bass, and if so, how so? Or what is the author actually referring to, in this passage? Thanks for reading!