According to some theories, how did flea markets get their name?

if there are conflicting answers how can there be one to choose as right?

I went to an outdoor flea market that had lice and mites crawling on the tables from the wild birds !

so flea markets and swap meets are the same thing?

I would rather have fleas than bedbugs.

IrreverentRascal4106, You just choose the right answer. Wether the answers are conflicting or not , there is still a right answer.