Let me start that I am built very small. 5'3", like a size 0 in pants, and no boobs. Shopping for a bra for me was hell and I didn't even bother wearing one for years. I pop by Victoria's Secret because of sudden girly urges.
I go in and talk to a sales person.
"Hey! I'm looking for some bras that'll fit me."
The woman looks me up and down, "You're like a 30AA [That's smaller than an A], and the smallest size we carry is 32A. If you want those, you need to special order online."
She didn't bother measuring me or anything, just gave me a once over. I ended up leaving the store feeling pretty shitty and unwomanly. I didn't bother to try looking for bras for months after that.
Then I came upon Soma's, actually got measured (32A! HAH, take that!) and found some bras that fit me. But damn, that woman at Victoria's Secret made me feel bad, she could have at least measured me before sending me away.