For me, it's one or more variations of the "farcical female orgasm(s)".
1. the woman orgasming on first contact: "she exploded in orgasm as soon as I sunk my 10 inch cock into her pussy"; "Otto's tongue touched Mathilde's clit, instantly triggering her orgasm" ... blah, blah.
2. usually when I encounter something like #2, what follows is a flurry of repeated orgasms, the woman cumming multiple times before the guy finally does. "orgasm after orgasm", "she kept cumming over and over again", "after her eighth orgasm, two in each of four different positions, I finally...."; "each orgasm more powerful than the last"
I may be setting myself up for rebuke and ridicule here (I fully admit that I am certainly one of the least sexually experienced Lushies IRL, so I could be wrong), but that's just not how things happen, right? Okay, there may be the rare woman here and there who climaxes very easily, who orgasms rather than recoils when the guy attacks her clit, but I roll my eyes when I read this kind of thing in story after story. I realize that some women are "multi-orgasmic" in that they can keep going after one orgasm and achieve subsequent climaxes, but that isn't the norm. The gal's orgasm is almost always much more elusive than the guy's.
Unless it's obvious parody, which I enjoy as much as anyone else, the absurd orgasm avalanche detracts from the story much more than it enhances it. If I were to be overly critical, I'd say it's just lazy to write as if the male protagonist (especially written as first-person POV) doesn't have to exert any energy to elicit such an improbable response. If the intent is to communicate the man's superior sexual abilities, hearing that he was man enough to work at pleasing her is much more plausible. Fantasizing that he's getting himself off on or in a woman who cums effortlessly is more about her providing cheap entertainment than him demonstrating sexual prowess. "I want to do it with a chick who gets off easily" isn't as relatable to me as "I want to be the guy who treats her to something special, where the orgasm is the culmination rather than the entirety of the experience". I'm not saying this dynamic shouldn't EVER be used, but IMHO it is way OVER-used.