I have a twenty-something daughter who is athletic, educated, and a very religious Christian donating much of her money and time. She is very busy and also a coach. The problem is her grooming and hygiene are very poor. Every time she comes home (a few times a year) we get into a big fight over it. I'm not very tactful but the only one who will bring it up to her. She has only had two boyfriends who lasted about four months each before they broke up with her. For instance, the other day we met her grandmother for dinner at a restaurant, and she refused to comb her long unkempt hair. She had rats nests all through the back of it. She says no one should judge her on her appearance and that I am obsessed (I am not). She has extreme body odor and unfortunately not much of a sense of smell. That is another problem. She will only take a shower after she works out. Her clothes have odors that won't come out. She has hoarding tendencies and prides herself on not buying anything new, just get old clothes from friends when they are throwing them out or donating them. I don't know what to do. She is extremely defiant and this is destroying our relationship and possibly her chance of getting married and having a family. She went on a mission trip to Africa one summer and seems to be more extreme now.
"Let your garments always be white, and let your head lack no oil" (Ecclesiastes 9:8).
There are several mental illnesses which have a lack of personal hygiene as one of their symptoms. However, these do not fit your daughter. It appears to me that she has selected poor hygiene as her way of rebelling against society. Though she is a caring person in some ways, she does not consider her impact on others as important. She justifies it because poorer countries spend less on hygiene, but she doesn't balance the realization that homes there are not as efficient so there is greater air flow from outdoors and that poor hygiene translates into poorer health.
Until she gives up her idealism and comes back to live in the real world, there isn't much you can do except restrict you time with her and that isn't something you are likely wanting to do. Treat her as an adult and not as your 10-year-old daughter. You stated what you thought, but you can't make her be reasonable, so you'll have to leave it at that.