I line manage a guy who's notoriously difficult (civil service), he's on a restoring efficiency program for a number of things, one of the points in there is his personal hygiene.
When he got to my dept it was eye wateringly bad so I had the difficult conversation with him about addressing it along with some of his other unpleasant habits.
I had to have the same conversation with him on two other occasions as it became quite difficult to share an office with him or let him go to meetings etc as people would talk about him, ask me to sort it out etc.
To his credit, it has improved over the last 2 months (he arrived in May).
I put a paragraph in his review about maintaining the standard he has achieved (which is to not smell, aside from that his turnout is generally poor and he looks "unwashed" but that's more difficult to address).
He got very angry with me and refused to sign his review (he doesn't actually need to sign it but it's a frustration) because he's made so much improvement...
I countered that he had improved but I'd already had to tell him 3 times, I wanted to ensure I didn't have to tell him again. A small part of me dies every time I have to tell a 32 year old that he smells so bad.
He said if I had to mention it again I could say "I told you so" which is entirely unhelpful.
He was really really hard work over a number of other problems as well, being argumentative about the error level that's acceptable in his job (I'm talking spell checking, not complex spreadsheets) and I'm just so fucking demoralised by it all.
Rant over. Just wanted to get it out of my system.