When you take the liquid Bentonite you should mix 1 tablespoon in a glass of water...it really doesn't have much of a taste. I can't imagine that yogurt or soy would make it any better. Actually, you shouldn't take Bentonite within an hour of any medications, supplements or food since it can absorb the nutrients, etc. If the taste is objectionable to you, you could mix it with diluted fruit juice.
One of the best ways to use Bentonite internally is to mix it with psyllium husks...makes a very effective colon cleanse. Check out the Bowel Cleanse Forum on this site for more info on this.