Many are cringeworthy, such as In the end, it turns out it was all a dream and Person is floating in a formless void; in the end, they’re born.
Others make you lose faith in humanity: Someone wants to kill someone else, and that’s perfectly reasonable because, after all, the victim-to-be is fat and Man is forced by circumstances or magic to rape a woman even though he really doesn’t want to, honest.
One, as Brian Q. Webb pointed out to me, was the plot of every other episode of Star Trek: Visitor to alien planet ignores information about local rules, inadvertently violates them, is punished.
Plots worth a special mention are: The alien or AI is fluent in English and completely familiar with various English idioms, but is completely unfamiliar with human biology and/or with such concepts as sex or violence and/or with certain specific extremely common English words (such as “cat”), and All technology is shown to be soulless; in contrast, anything “natural” is by definition good. For example, living in a weather-controlled environment is bad, because it’s artificial, while dying of pneumonia is good, because it’s natural.
Speculative fiction writers of the past had it easier than modern day authors, who are challenged to find ideas and characters new to seasoned readers. I recognised a few of my own short story plots on the Strange Horizons list, but at least I know what to avoid in future.