how well/long do you have had to know someone before you'd say 'erm, you have a little bit of a dangler you might want to sort out'

i was just talking to someone at work yesterday who i've only had a couple of conversations with, recently and she had a tiny bit of thing hanging from her nose but i felt bad/like i'd seem like a b!tch if i pointed it out to her.
but the other day i did tell another friend at work who im closer to and i would tell that sort of thing to anyone i consider a real friend.

also what would you do if you had a friend who smelled really badly? im sure we all know someone who has a bit of a bruised orange situation going on, but do you say anything?
i think if i had a good friend who smelt i would let them know, luckily i havent so far but i'd like to know if was walking around smelly dirty.

THOUGHTS?