Seafood market is from a variety show, in the program a man said a sentence: "I introduce you to seafood girls, not seafood market", and then broke the Internet. Because seafood is an aquatic product, it has flavor.

"Seafood market" is actually a flirtatious remark. Seafood is more or less a fishy smell, not washed before it is still dirty. So most of it means that it's not clean, dirty, and has a heavy flavor. Or that some people are a bit promiscuous and do not pay attention to their personal hygiene.