Brad Johnson said:Seriously, sometimes the differences are nuanced, while other times it's pretty dramatic. If you've never noticed basses sounding different, that's you, not the instrument. It happens quite frequently.
99% of the audience can't tell a Hofner from an Alembic with ears alone, but 99% of us bassists can.
The answer is usually electronics, but we're talkin' fingerboards. The majority of us believe that when a maple board bass sounds brighter than a rosewood board bass, it's because of the fingerboard (for the purpose of this post, all basses are fretted). So... what's the explanation when a rosewood board bass sounds brighter than a maple board one? (It happens often... if you've never heard it, then it's you, not the instruments.
Short answer: it's the inconsistency of wood. All the tap testing in the world can't eliminate that inconsistency. I've noticed differences in tone from identical basses strung with identical string sets. Ken Smith said he's noticed differences between identical basses built with wood taken from the very same planks.
The logical conclusion is to listen with your ears, not your eyes. Ok, this doesn't apply when you can't try before you buy: in that case, go with your opinion, or that of your luthier. But most of us who have placed a custom order or built a parts bass will testify that actual results often vary from expected. It's not chemistry or math: there are many possible results for A + B + C, regardless of the skill of the manufacturer or quality of materials.