Star Trek: 10 Things You Didn't Know About Section 31
9. By The Late 24 Century Their Existence Was No Longer Secret
The thing about clandestine organizations is that they are at their most effective when very few people know about them. For most of its existence, Section 31 operated from the shadows, its operatives willingly carrying out actions that would turn the average Federation citizen's stomach. If the average Federation citizen ever heard about Section 31, it was a rumored branch of Starfleet Intelligence. That's how Section 31 operatives liked it.
What Section 31 operatives probably didn't like, was for fresh ensigns from the lower decks of a second string class of starships to openly mock them.
However, by the 2380s the once-secret agency was so widely known that Starfleet ensigns could openly joke about their agents' behavior such as their operatives alleged habit of conserving energy by speed walking. An activity associated with gentle fitness hardly fits with the slightly sinister, hyper-competent image operatives such as Luther Sloan liked to project.
Not everyone in the late 24th century mocked Section 31. In 2381, William Boimler, Brad's transporter-created duplicate, joined Section 31 after briefly questioning some of their tactics. In 2401, Worf, praised them as an essential section of Starfleet Intelligence.