Silly ADD question

This is going to sound silly, after all the hot discussions we've had lately, but here goes...

How can an ADD person not remember to let the water out of the bathtub? I never find this out until I go to take my shower, and can't.

If I ask him, he'll say he did let it out, even though he clearly didn't. How can someone who is properly medicated be so far out in ADD Land that they don't know you are supposed to let the water out when you are done? It means it gets more soap scum, etc. and I have to clean it.

Not an earth shattering question, just wondering if someone can shed light on their thought processes (or lack of).