Supposing you had good friends who were, er smelly, very smellly. Lots of dogs and cats in their old house. They are good people, kind, helpful, supportive. You enjoy their company. Would you tell them or just take them as they are? Smells and all?

Well, Auntie Agnes, that's a tricky one.

I'd just douse them in gasoline and offer them a light.

I hope you find that helpful.

Do write again.

I doubt they need gasoline to be combustible however your input is duly noted.

Just breathe through your mouth when you visit !

My (big) dog's just farted... but I still love her.

I'd just put up with it as saying something would cause a fuss and nobody wants to be told they are stinky. If you feel that you must do something, then make it as passive/aggressive as possible. I suggest wearing a clothes peg next time you go around their house. If they ask about it, just say, "oh this? it's nothing, forget it's here, it doesn't mean you're a bit whiffy, no honestly"

I don't. Can't you control that animal? Tut, tut.

Everything but her bottom...!!

Ah yes, I did consider a bottle of febreze as a gift but your idea could go well with that.

My car stinks of wet dog and I don't care. It's still not as smelly as people that use public transport.

You have public transport? Be happy and don't forget your clothes peg.

the lyrics of this seem appropriate here

There's a bus, but I don't use it. Apart from being smelly, bus users here often have a haunted look in their eyes as if they've seen terrible things.

I used to work with a girl who suffered BO, really bad BO. We all talked about what we should do, one of the girls eventually got brave enough to say something. The BO sufferer was mortified but thankful that she had been told, she hasn't stunk since. She just didnt know.

No, if anything encourage them to be even more smelly. Smelly is brilliant.
Even better if they have some twigs in their hair but that might be too much to ask.