I agree, they taste horrible! I only take one tablespoon at night, and mix it with apple juice instead of water. I also drink it through a straw and put the straw in the back of my mouth. Then I suck on an altoids mint. I don't usually eat candy so that's like a reward.
Sometimes I don't use any epsoms, I substitute mag citrate powder or leftover Oxypowder
capsules. I sometimes use phillips milk of magnesia capsules in the am. In fact, come to think of it, the only consistent thing in my flush is the oo/gf. They all seem to work the same to me.
Also, lots of people do the flush without any epsoms or anything and have great results so it's not mandatory! I like to use it just in case I have a really big stone so it doesn't get stuck. Other than that I think any of the substitutes work just as well in my experience.
Just my 2 cents!