I’m putting this one right here for context. The second story of the first episode is titled 「立てば芍薬座れば牡丹淫れる姿は毛氈苔」. It came from an old saying 「立てば芍薬、座れば牡丹、歩く姿は百合の花」 which literally translates to “A garden peony when standing up, a mountain peony when sitting down, a lily flower when walking.” It describes how a beautiful girl can be compared to different kinds of flowers on different things that they do.
It’s similar to “beauty is in the eye of the beholder”. But my personal interpretation of it is that “beauty is a quality beyond the superficial” and that “when something/someone is beautiful, they will be regardless of what they do or where they are”.
Going back to the title, the last part “a lily flower when walking” was changed into “a round-leaved sundew when acting indecently”. The message behind it is that a beautiful woman will still look pretty even if she is doing the nasty. There is the analogy of the aesthetically pleasing carnivorous plant, the round-leaved sundew implied in it as well.