Since sex is a topic that people find interesting, it stands to reason that a character whose primary established trait is the desire and ability to have sex with multiple people will be interesting to the audience. This principle also works when applied to other elements, such as plots, settings, or even the show as a whole.
Ironically, commonplace usage of this trope is such that often it ends up not being interesting at all. A few decades ago "has lots of sex" was a rare enough character type that writers could design individual elements around it while still having a vibrant story. In modern times, Everybody Has Lots of Sex has negated this appeal.
This trope will often come off as a thinly veiled attempt to boost viewership via Hotter and Sexier. While Sex Sells has made something of a mockery of this trope as it relates to genuine character development, sex as a narrative topic can be genuinely interesting provided that there's a logical reason why the show has such a strong emphasis on it. More importantly, the issues need to be presented in a way that arouses the audience intellectually as opposed to, well, the other way.
Bisexuals, when they appear in fiction at all, tend to get shoehorned into this trope because writers still aren't sure how to use them. The same is true for homosexuals, although some progress has been made in portraying them with more diverse personalities.
Contrast with Sex Is Boring and No Hugging, No Kissing. Not to be confused with Everybody Has Lots of Sex, which is just an assumed part of the background as opposed to a deliberate focus. Often overlaps with Sex Is Good. This trope can be used without Fanservice, but it's hard to imagine why anyone would do such a thing.
- Pineapple Express has this trope in the Director's Cut, but only to mock it. When Dale expresses disbelief that Amber is really as mature and complex a person as he thought she was, the high-school age Amber angrily insists that of course she's mature, much moreso than Dale, since she's had sex with seventeen different guys.
- Thirteen from House was criticized because her character seemed to be centered around this trope, often talking about sex or past sexual encounters (usually with women) whenever there's a gap in the script.
- Nip/Tuck originally only used this trope with Christian, but as the series goes on nearly every character has gotten in on this with sex being used as a complement (or replacement) to Character Development.
- Angela from Bones lives this trope at times, especially with her relationship with Roxy and her later decision to be temporarily celibate are introduced. She's able to avoid many of the pitfalls of this trope because she's an Ethical Slut who embraces an alternative lifestyle as opposed to just being into sex for the heck of it.
- Steven Moffat, showrunner over a Hotter and Sexier era of Doctor Who, has stated multiple times that the reason he doesn't write the Doctor with the No Hugging, No Kissing asexuality of the Classic series is because it is boring. According to him, a non-sexual Doctor is denying the Doctor the opportunity to "live a full life" or be a Rounded Character. A lot of real-life Asexuals, who can be quite interesting without having any desire to kiss people, were very offended by this, though Moffat was probably talking from the perspective of this trope rather than trying to pass judgement on anyone real. The trope also has a lot of Author Appeal for him, as he became big writing Sex Comedy. However, the Twelfth Doctor's run initially saw a return to No Hugging, No Kissing, until this was eventually dropped as his romance with Clara Oswald reignited (though it was depicted in a very subtle fashion).
- Much more than any other RPG by BioWare, Mass Effect 2 deals with sex almost constantly. The biologist Mordin, despite his race allegedly having no sex drive, is interested in the topic academically and thus has lots of (hilarious) comments about the crew's sex life and numerous pieces of good or at least well meant advice for Shepard should they pursue a relationship with a non-human crewmember. Then there's also a blue skinned space vampire who drains her victims life energy by having sex with them.
- The screenplay writers themselves seem to consider sexual mannerisms an important part of insight into the culture of various races. In every space port you will encounter NPCs discussing their relationships with their alien husbands or wives, or the social disgrace of two asari having a child together. Or some insight into the breeding customs of the Salarians or Krogan gender roles, thus providing the player with both exposition and a copious amount of hilarity. Of note is the refreshing maturity with which such topics are discussed, never quite veering into dirty joke territory.
- In The Family Party by A-gnosis, a comic about Greek gods, Hades states that "Sex Is Boring", which baffles the other gods, most of all Zeus, who cannot wrap his mind around that idea, and promtly suggests that they need to go ask Aphrodite whether Hades has some weird fetish.
- Ménage à 3 and its spinoffs, Sticky Dilly Buns and Sandra on the Rocks, are Sex Comedies in which Everybody Has Lots of Sex but they are also character-based lightweight dramas in which the characters rather obsessive pursuit of sexual satisfaction drives many or most of the plots.
- In the Global Guardians PBEM Universe, Vindicator's characterization and story was centered around her status as a Token Lesbian Superhero. It got tiring after a while, and then got Squicky when it was revealed that the player was a sock puppet for a creepy internet guy just looking to have his jollies by being creepy.