If you use the appropriate wood, you can wet and sand many times to get a smooth finish. You can burnish it (rub with hard metal) to close the surface well. But it will still stain and absorb smells, just to a lessor extent. You'll notice if you use the same spoon for coffee and tea, or the same spoon for curry and miso soup.

Why would you use a wooden spoon for those? I use wooden utensils for frying and stirring in metal pots and pans. Everything else is just the usual stainless steel type suitable for utensils.