On the topic of clothing stores, I prefer to go to non-religious stores over frum stores.
Secular store workers or owners here me say “Yeah, I can’t wear that” or “It’s not tzniyus” or “Too short” and accept it.
The reason is because if you go to a goyish store they don’t care if you think it’s not tznius, they’ll sell it to someone else who thinks it is whereas a Jewish store if you tell them it’s not tznius they will take it as “you’re selling untznius clothes which they need to justify for themselves (not for you)