Yeah, immersion was always a grey zone as far as how realistic the premise was. But since their was a JLU episode to base it on where Lex and Roulette picked a fight club instead of a bordello, it was fine.
Updates like this (bar the horrible downward trend the art has made) break whatever believabilty the plot had.
So the whole idea was that the devices make it so that the girls not remember what happens during their nighttime in Lex's dungeon, ok, so far so good.
Now, Lex brings Barbara as his date to the villains ball at night. Its fine she will not remember it during her waking hours and the JL and Batman ar non the wiser. However, Barbara can interact with both her father and Bruce, there are even moments where Lex is busy in his booth with whomever of the other ladies so Babs is free to wander. What is stopping Babs from spilling the entire thing to har father or Bruce, since while at night, she is aware of it all?