Personal compliments.

James Valentine did a segment on bald men once because apparently bald men get told they are bald and its annoying. Der! They aren't the only people to have people point out a very obvious physical trait on a regular basis. I have been guilty of pointing out that someone is very tall. Other targets for comment are pregnant women, red-heads, curly heads, short people, freckly people.

In my study of the works of Jane Austen I have discovered that any personal comment at all was rude. If you met someone and said "that's a lovely dress", rude. Compliment someone's hair or whatever, no. Physical appearance was off limits. The only characters who do it are the vulgar ones, Lucy Steele for example. Today, maybe it's just that all my friends are vulgar, but we quite happily say "nice dress!" and then the person says "I made it!" or "it's from blah shop!". That's the formula someone told me girls have. Swap compliment for source. But maybe it's still rude? Maybe it still implies that your other dresses are less nice? Maybe it does make people feel self-conscious about their appearance for a moment? Maybe the rule is you can compliment people on things that they have made a choice about, but never point out something they have no control over?