I put I don't know how many coats of rattle can satin poly on my maple on maple neck and the fingerboard is filthy up to the third fret and it is starting around the 5th fret also. Oh well, I never intended on selling this guitar. I wanted it all maple, flame top, maple body and maple neck and fretboard. It' is a really cool monochromatic look, but I didn't take into consideration that the fretboard would get so grimy so fast.
Any way, short of spot sanding the dirty spots and re spraying the neck to clean it up a bit? I don't know if I wore through the finish, or if the finish is really dirty.
I do know that I am pretty sure that is my last maple neck (other than my 51 nocaster project I have cooking in my mind right now, but I'm not going to finish that guitar at all, I want to naturally relic it by actually playing it, not belt sanding a perfectly finished guitar the way they do it now!!) Rosewood doesn't show dirt nearly as bad as maple.... Besides i have 3 maple homebuilts, I think it's time I start thinking about some other types of wood