There's a girl who stinks and I'm going to tell her.
Please don't tell me that's the only thing you're going to say to her.
It's what she needs to hear.  Otherwise, she's as beautiful as the starry sky
If you think that this girl needs to take better care of her personal hygiene, then you should let her know, even if it is uncomfortable to do so.  However, there are better ways to raise the issue than just telling her that she stinks.
She'll understand me and it's more comfortable to call a girl stinky trash then a beautiful starry sky.
If you need to tell her about hygiene issues then you should do so, but only do it in a way that is respectful of her feelings. This runs great risk of embarrassing her and hurting her feelings. If you can't be tactful then you should refrain completely.