Its a bit hit and miss, if the truth be told. No piece of wood is exactly the same and there's no way of knowing what the instrument will really sound like until its built. Plus how its built will change the response of the instrument as well.
However, some companies have managed to achieve remarkable consistency in their instruments - Wal, Celinder, Musicman and Dingwall to name but four. They tend to use a fairly simple approach to construction and the same woods. Dingwall and Musicman aim for a specific weight for their bodies and necks. Alembic and Status produce very consistent instruments as well but their construction is more complex and doesn't always rely on wood.
Having said all that, its still possible for an experienced luthier to get within a reasonable ballpark of a particular result. But they need to have a lot of experience using the woods they've selected to know how the qualities they percieve in sawn lumber translate into a finished instrument. Ironically luthiers who use a very wide variety of woods often don't have enough experience in using each species to deliver a specific outcome. So they'll be able to make you a great bass but whether it delivers what you want to hear is another thing.