There was one episode that I found a bit offensive. It's about a planet that had only one gender. When people started to gravitate toward male or female, they would "fix them" by some sort of brainwashing. It was a very politically-motivated statement. I didn't much care for it.
That is somewhat incorect, the race was the J'Naii only mentioned in Season 5, Episode 17, "The Outcast". In the episode they state several times that the J'Naii are genderless.
This episode is criticized because Jonathan Frakes and Michael Dorn esentially break the Kayfabe of their characters, Ryker and Worf. Their characters were too "by the book" for their actions in the last portions of the episode.
Another one that didn't offend me, but was along the same lines, was about a society where people would prevent senility by scheduling people's funerals at age 72. It was a family event where everybody would get together to say goodbye to the old person, after which the 72-year-old would basically commit suicide. It was pretty far out there. The episode starred David Ogden Stiers as the 72-year-old, who was vibrant and intelligent and VERY FAR from senility on his deathday.
In this case it was not a member of the crew who interviened. Loxanna Troi, the ships councilor's Betazed mother, who is NOT a Star Fleet Officer or Crewman, gets romantically involved with the man in question. She tried to convince the man to go against the tradition of the society, initially suceeding, but he finds himself shut off from his work, which he finds the same as being dead. He goes along with tradition. Loxanna apeals to the Captain, who in his usual stoicism, says that he cannot get involved. Loxanna choses to attend the man's "Resolution" and he is pleased that she respects the tradition of his culture even if it conflicts with her mores.
In this episode none of the cast members broke the Kayfabe of their characters, something you should not do in either wrestling or Sci-Fi. Which I think is fitting because don't they show ECW on the Sci-Fi channel.