I use the unscented Bronners for brushing my teeth, and there's hardly any taste at all. Some of the others are pretty nasty. It takes all of about 3-4 drops, which is nothing in the backcountry. I have a small dropper bottle in my pack and use it for body and oral hygiene.
AND after reading a post online about a guy solving his sensitive teeth problem by brushing with soap and STOPPING his use of toothpaste, I gave it a shot using Bronners. I've had sensitive teeth for years and even the toothpaste for sensitive teeth doesn't seem to help much, if any. Once I stopped using toothpaste, the issue was TOTALLY gone within a couple weeks and hasn't returned. An online explanation I read had to do with the glycerine in the toothpaste that is deposited on the teeth every time you brush and prevents the calcium in your saliva from being deposited over the sensitive areas. Beats me. All I know is that nothing I've ever tried worked until I totally got rid of the toothpaste. I haven't had a single incidence of sensitive tooth pain since. All the sweets that would get stuck on the sensitive part and cause pain don't give me any problems at all now. Freakin' awesome!!!!