Downplayed: Bob and Alice seem to enjoy having sex but the scene is not explicit or very long. Zod, meanwhile, only manages to get sex from prostitutes, and he always ends up unfulfilled.
Justified: Zod is a sadistic misogynist in real life, and it's reflected in the bedroom; the same Freudian Excuse for his evil ways is responsible for his not understanding romantic relationships. Alice and Bob are embarrassed to bring up their fantasies to each other because they're worried what the other will think.
Subverted: Alice and Bob are shown having G-Rated Sex... then they hear a door slam. "Finally, he's left! You pick out a costume, I'll see what's in the vegetable drawer."
Double Subverted: ..."Very funny, Bob. Now turn the light back off."
Parodied: When Alice and Bob make love, choral music plays and holy light shines through the window. When Yolanda and Zod have sex, all the nearby plants die, wolves howl in the distance, and murder victims roll over in their graves.
Zig Zagged: Zod and Yolanda have some freaky, disgusting sex... but then we see Alice joining in! She explains she's bored with Bob because he can't get it up... but here's Bob telling Charlie he's turned off by her talking dirty. Charlie asks if he's sure he's not just gay, and Bob and Charlie... explore this possibility. Meanwhile, Alice has left, and Zod and Yolanda are cuddled together whispering sweet nothings like the High School Sweethearts they are.
Averted: No correlation is implied between morality and sexual behaviour.
Enforced: The writers wanted Alice and Bob to be more open-minded, but the Moral Guardians complained.
"Y'know Bob, just because you're The Cape doesn't mean you can't occasionally [filth redacted] - there's nothing immoral about it".
"Welp, pretty sure I've crossed the Moral Event Horizon there. Oh well, at least now I can enjoy all that freaky Villain Sex!"
Alice and Bob play Shipper on Deck to Zod, reasoning that if they find him a nice girlfriend he'll stop being evil.
Yolanda pulls a Sex Face Turn when she discovers how much better sex with Good Guys can be.
Exploited: Bob and Alice are the last humans left alive and decide to rebuild the human race with the most heroically erotic sex scenes ever written.
Defied: "What? Just because I'm a good guy doesn't mean I don't like a bit of Destructo-Nookie now and again!"
Discussed: "God, I bet those two Goody-Two-Shoes have revoltingly G-Rated Sex..."
Implied: We never see a sex scene but we do see Bob and Alice post-coitus and they seem very, very happy. Zod, meanwhile, gets his own post-coitus scene showing him still chained to a wall with a gag ball in his mouth and looking miserable.
Deconstructed: Alice leaves Bob because he refuses to try new things. Zod realises he's using Yolanda to enact his worst fantasies, and leaves her. After running into Zod on the rebound, Alice is disgusted with herself and apologises to Bob, but discovers she's pregnant with Daddy's Little Villain.
Reconstructed: Bob and Alice have a fairly vanilla-flavoured relationship, because they enjoy being tender and intimate with each other. Yolanda and Zod like to get their violent tendencies out of the way in a controlled environment because it makes for more efficient Evil Scheming. Both couples have occasional problems, and deal with them in ways that reflect their usual interpersonal skills; Alice and Bob are understanding and supportive, Yolanda and Zod are recriminatory and selfish.
Played For Laughs: Bob and Alice get a zany sex-romp scene with a quick cut to Zod being frustrated in bed as he tries to "rise to the occasion" with a very bored Yolanda.
Played For Drama: Bob and Alice have a very tender, beautiful sex scene together, showing their kind hearted nature. Later, we see Zod with Yolanda and we learn that Zod is a sadistic brute to her.