I agree with everyone else; very common and normal, and either she is going to change on her own, or it will take someone saying something to get her to do it. My girls are 7 & 9 and this spring we read the "American Girl, The Care and Keeping of You" (as someone else already suggested). It took the pressure off me having to tell them these things and made it all more neutral - plus most kids listen better if the info is coming from an outside source, rather than their parents "nagging" them about something. I also agree with what others have said, some things are not negotiable in our family - like you must brush teeth. I would require a certain amount of showers/bathes a week (at least every other day, including washing hair). I would talk to her about the risks of other people not liking her, not wanting to be around her, not wanting to talk to her if she stinks. It is better to hear that stuff from you now, than to wait until she is miserable and alone. With my girls, we read a few parts of "The Care and Keeping of You" and made a shopping list and to do list after each part. We went out and bought new toothbrushes, deodorant, combs, etc - they got to pick them out and got to have their very own. We made a list of what things we hadn't been doing, but should (like flossing more often). I even allowed my 9 yr old dd to pick out some bras, not that she needs them yet, but I figured it would make these things easier when they really do come up, if we have already been talking about them for years. I think making sure she knows it is not just her, this happens to everyone - girls and boys - that would help. Good luck, this is such a tender age.
S.