I was pondering this earlier in the week. People have summaries they like and ones they will scroll past without considering the story at all.
I'm rather open with summaries. I think the only ones I dislike are either when there isn't one or when the words aren't actually a summary, but author's notes. I prefer those for after I've clicked on the story.
I've read in the past people want them to be snappy, but I was considering longer works. Complicated stories. In those cases, I prefer a few paragraphs to introduce the basics of characters and plots. On the other hand, if the story is short, a longer summary doesn't make sense.
What types of summaries do you like? Which ones do you like to write? Does anyone else think writing a summary is easier than coming up with the title of the fanfic, or is it just me?