Being messy, I get. Why bother picking it up? I know where it is. If I pick it up now I'll just have to take it out again later.
But personal hygiene? Gifted kids usually have the sensory overexcitability, which leads to being unable to stand being dirty. My DD went through a period around age 2 where she insisted on being carried from the slide to the swings, so our challenge was the opposite... teaching a kid it's okay to be dirty.
Besides, showering should be a pleasant sensory experience when you're doing it right. Maybe she's doing it wrong? There are a lot of things that can turn it into something unpleasant... water too hot/cold, towels too thin, scratchy loofas, smelly soaps/shampoos, bathroom steaming up too heavily, etc. DD6 has a habit of emerging from the bathroom, soaking wet, to ask for help drying off. That's a pretty unpleasant experience during winter, so she's trying to learn to stay in the bathroom where it's warm and call for help instead.
So it's probably worth it to talk to her about it and see if there might be something that can be done to make it better for her. And maybe there's something that can be done with the toothbrush, too... let her try other toothpastes, get her an electric brush if she doesn't already have one, etc. Unfortunately, I don't know anyone who enjoys a good tooth brushing, so there's probably no easy fix there.
At our house, on weekends, we generally don't have any kind of schedule, and people pretty much groom themselves depending on how the day progresses. This lends itself to some teasing about who is still a "stinky butt," which gives us a playful way to impart the social consequences of not showering. It doesn't matter whether the person has a noticeable odor or not... if you haven't had your shower yet, you're a stinky butt.
