Well, yes and no. First of all, suspension of disbelief is highly subjective. Also, maintaining it is often proportonial to the quality of the writing. Most porn plots consist of nothing but flimsiest excuses to show some skin, and you're not supposed to pick them apart. Likewise, many game plots mainly exist to move the player along to the next level. And that's when most people are like, "Whatever, I'm just here to shoot some zombies/see some tits/shoot some zombie tits."
But sometimes the game/porn writer doesn't just shoot for clearing the low bar, but is ambitious enough to tell an actual story. While it's still a game, and while it still has a plenty of T&A, there's also a fleshed out narrative - and suddenly maintaining that suspension of disbelief becomes a fair bit more difficult when you come across something that starts bugging you.
And if you're the writer of said story, you might even find it flattering when people start wondering about this stuff, because it means there are people out there who are actually reading what you write, instead of being like, "Space bar, space bar, space bar... LEMME SEE SOME TITS!"