Being a tad overweight (ahem), I used to buy looser, longer tops & trousers - until I was in London & saw the reflection of a woman in an angled, plate glass window. I thought with a mental sneer, 'She's wearing all the things fat women wear because they think it makes them look thin' - then I realised it was me.
I went for more fitted things after that.
I had the same kind of experience once at a conference. There was a woman there with what I thought to myself was a really dated & dowdy hairstyle. It took a while to register that it was the same as mine. It was the push I needed to get mine cut in a fashionable style.