Hmmm, a healthy bun should not have a perpetually dirty bum. Is it more from urine or poop?

Excess cecotropes could be the problem, or she might have a urinary tract infection. A vet visit might be in order.

What is her litter box set up like?

Is she spayed?

It isn’t normal for a healthy rabbit in clean conditions to be wet from urine. She could have a UTI or some other issue. I really recommend getting a second opinion from a rabbit vet.

I agree, that’s not normal, and has nothing to do with her being spoiled. Rabbits don’t wet themselves for no reason.

@NoraandTheo, for reference, this is a reliable source of possible causes (although others are possible):

http://www.bio.miami.edu/hare/urinary.html

OH I just commented about my bunnys dirty bum on another thread. My bun has weak hind legs though, so that’s why she wets herself.
She always had a yellow stained bum/feet since I got her and I had to give her a bumbath every 3-4 weeks but now her bum has been white for 3 weeks by herself, usually her bum/feet would get yellow stained again a day after her butt bath.

Have you tried using a plastic grate on top of your tray since she is a healthy bun.
I bought them at those Asian convenience store, they both fit together so no need to alter anything, they have heaps of shapes and sizes, and fortunately I found one with holes that fitted perfectly in the tray. Was only $9AUD ($6USD) for the both the black tub and the tub with holes! I bought one for my friend coz she didn’t like the idea of her buns stepping in their own urine. She lines the black tub with a puppy pee pad. But you can make do another way.

https://imgur.com/6ZGx4EZ

This method worked for my disabled bun:
Pine pellets 3/4 of tray, hay top half. Throughout the day I will use the uneaten hay to cover her days poop/pee (this helps masks the smell and stops her stepping on her cecotropes)

I used to use a plastic found the grate on top of tray but it seemed to have made my bun dirtier (just didn’t work for me). She doesn’t eat alot of her cecotropes, so I’d pick them up if I see them in the morning otherwise she will smoosh it and it will get stuck in the grid holes and then on her bum/legs causing matting which she can’t clean. I removed the grate coz it looked like it was hurting her her feet but it worked out better in the end.