E.P.
I know this may sound gross but it worked in less than a month with my daughter. While I changed her #2s, I'd get all excited and say "OOhh you have a blue poop today." Since she knew her colors so well, I'd even tell her she had magenta and chartruse, even rainbow poop. I told her the only way she could see it is if she went in the potty. That was all it took. And by the time she went, we made such a big deal about actually going on the potty, that it didn't bother her that the stuff in the bowl was pretty boring. Hope that helps.