You may know how baozi looks like, an enclosed whirlpool. You will never know what the stuffing is until you give it a bite.
Baozi itself can also indicate personal philosophies of Chinese people. A common philosophy is for people to indulge in moderation and internalize their pleasure, which means the virtue of a person or good baozi stuffing should be hidden. Otherwise they will be considered blatant. It will also be regarded as a rude manner to ask questions directly.
If you cannot tell how many meat layers in a hamburger, you shouldn’t buy it. How chary the seller is.