I saw that Eating but really it should have been a concerned aunt. I never saw any hint that Madge, who would see more of it, thought it was an issue. It's Joey that makes a thing about it, which always come across as jealousy-particularly as she's always described as "never beautiful"-to me.
It always seemed odd that we're told it's an issue for Sybil, when Robin gets huge numbers of comments on her looks and is always described as unspoilt. And Peggy and Primula are also described as particularly lovely to look at, so if they'd gone out as a group surely no one would have just commented on one.
It would have been better if EBD had found an accident that could be directly attributed to Sybil thinking about her looks. Maybe refusing to take the kettle off the fire because "it makes my face go all red and sooty" so Josette goes to do it for her.
For me, my ds gets and always had done as many comments about his looks. Perhaps differently-no one ever commented on the length of his plaits for example
Although he tends to growl and hide his face away if people do comment.
I do think you get more opportunities to comment on girl's looks in general, as they're more likely to have done something interesting with hair or wearing a party dress*
I suspect if a boy is wearing a superheroes costume or something unusual then they'll get an many comments about that as a girl will about her party dress.
However in my experience of 2 girls and a boy, my girls up to about age 8-10yo insisted on pretty dresses and a nice hair style (dd1 used to insist on ribbons in her hair from about 18 months, when I put one in for the first time for a friend's wedding). Whereas ds, as soon as he got any say, would live in shorts and t-shirt all year round. Forking him into a suit for dbro wedding the summer was a matter of patience and bribery. 
But he got an many comments about how nice he looked as the girls did as bridesmaids.
*I recognise in MN-land boys have long hair and party dresses as much as any girl, I'm talking about RL here. 