@KoiwiGal - It can be so difficult to approach someone about this though, or to hear it from a friend (or a stranger for that matter). I also think people have to beware that what they think is very important might not be important to others, or that an issue might not have a solution.
When I was a child one of my best friends had a problem with her kidneys (I don't know exactly what it was) and she often smelled a little bit of urine, but there was nothing she could do about it. That is an extremely tough position for a kid and people telling her about it, even if they were trying to be helpful, only made it worse.
The same goes for people with problems like acne. Sometimes it's just a medical condition and there's no solution. So commenting on it is only going to be rude and hurtful and it's better to just ignore it. It's not that difficult to be kind or considerate and give people the benefit of the doubt.