What's the nicest way to tell someone that they are musty?

I always just ask them if they're going to shower. Not in a rude way just like a casual question.

Whats musty....????

"hey man I gotta tell you about this amazing deodorant I just bought!" 😂😁

Do you use washing powder that smells of damp clothes?

The nicest way:

You: Are you wearing cologne?
Guy: Uh, no, why?
You: It doesn't smell good man
(follow by suggestion of what you think he should try)

Are you still referring to the woman you were supposed to have sex with the other day but smelled like ass? 🤔

Yo, take a shower, you’re
making the dog fart uncontrollably.

"Oh, btw, did you know that you smell like moldy cardboard in a damp cellar?"

How about, YOU SMELL LIKE MY BISCUIT TIN.