You buy a new one. There's controversy with iso staying inside the silicon so it's generally accepted to just get a new whip when it gets dirty.
I let mine get dirty enough that it actually clogged the whip part a few months ago. Some nice hard blows through it and some big chunks of hash fell out. Been hitting good ever since.
I think he's talking about cleaning the walls with something (which I have found hard to do unless with iso, and refer to my first post regarding iso). I don't think it's THAT bad, but I understand having a reeking tube with me all the time, it's cumbersome to try and cover up the smell.