Ground in dirt on maple fingerboard - sanding the only option?

[keko]

Dirty maple fretboards are the best... I say leave it. It's about as "road worn" as it's gonna get.

I agree!

That's what I'm gonna do with mine, ...nothing!

Just play your bass, through the years it will sound better, and better!

Maybe after +10 years you're should have to change frets, and that's your chance to do some deeper chemical cleaning, but don't ever sand your bass! I've made that mistake on my previous Warwick Streamer and ruined it forever!