Question for any potty training mom!

I have to ask this question to any of you who are currently potty training or have loads of experience in this arena!! Dear, sweet Cooper was the easiest by far out of the three to potty train. We had a couple of accidents, some bribery with Geo Trax and now he is completely potty trained. The problem is, he is so independent that he believes he should dump his poop himself. Most of the time, he does get it into the potty, however, today it ended up in the sink...gross, disgusting, yuk!!! This is the sink where the children brush their teeth - I am totally disturbed by the whole thing. I have dumped bleach and any other cleaning product to sanitize, but I just can't help thinking that there was poop in the sink. I try to tell him to tell me when he does it (he needs privacy so he always goes whenever I am in the middle of something!!), but he is not getting it. Any suggestions? Who knows where it will end up next!!!