In the climax of Tim Burton's first Batman movie, Kim Basinger's Vicki Vale seduces Jack Nicholson's Joker. She runs her lips up and down his clothes, declares her love for the color purple. The camera settles on a medium close-up of Nicholson, as Basinger slowly drops to her knees below his waist and below the bottom of the screen. Nicholson's permanent rictus smile almost breaks into an "O".
In Batman Returns, Michelle Pfeiffer's Catwoman seduces Michael Keaton's Batman. Her hand lovingly runs along his suit's articulated abs down to his articulated genitals.
In X-Men 2, Ian McKellen's Magneto suggests that Rebecca Romijn's Mystique entertains him by morphing into young good-looking men. He purrs at a protege of Xavier's, letting him know that he's a god among insects, essentially that he has a wonderful body he should be proud of.
These are just plot points. I would also say that Burton's camera makes love to Pfeiffer, stuck in a beautiful, shiny S&M suit. The soundtrack captures every bend and stretch of the latex. Bryan Singer's camera studies Lady Deathstrike's contortions as adamantium lead destroys her body from inside.
The scripts in Iron Man and The Amazing Spider-Man 2 make clear that, respectively, Tony Stark, and Peter Parker are not virgins, and yet you would be forgiven if you believed that Robert Downey, Jr. just wasn't that into it or that Andrew Garfield didn't get past first base with Emma Stone. Chris Evans's muscled body in The Avengers and Captain America: Winter Soldier is no more alluring than Leni Riefenstahl's athletes.
Nicholson's Joker is a sexed-up madman. Heath Ledger's Joker is an evil soldier in warpaint, and though he likes to kill, you can't really imagine him raping anyone. Christopher Reeve couldn't hide an erection. Henry Cavill is a eunuch.
Good superhero movies are carnivals. Good superhero movies are orgies.