ACV and adult hens

[TLWR]

I have a 1 year old BR and 2 BOs
The BR has a messy butt, or more accurately, messy feathers. Not pasty butt like you'd see in a chick, but dirty and not right.

If I add ACV to the water, will that help?
In the meantime, just scoop her up and clean off her back side?

The other 2 are perfectly fine/clean.

 

[Kelsie2290]

Do you think she has the beginning of vent gleet ?https://www.backyardchickens.com/a/vent-gleet-aka-nasty-chicken-butt I'd trim and clean her up to get a better look at what is going on.