This happened to me yesterday. Was admiring myself in communal mirror.
Pretty girl comes out trying on posh occasion frock, fairly bright pink. Absolutely gorgeous dress, but she was petite and flat chested with very english rose colouring and it did less than nothing for her. Managed successfully to keep trap shut, but then she appeared out in another dress. Again, stunning frock but deep emerald, completely wrong colour and shape for her, definitely would have been better in a muted colour and less showy.
I did manage not to say anything, thank goodness, but very difficult. I know etiquette and good manners dictate that I say nothing, but clearly she had no clue about what suited her and it offends my sensibilities to think of someone spending loads of money on clothes that don't suit them.