I do confess to thinking a lot about this topic, although not in a nostalgic way; I usually see a high star rating in my history on Goodreads for a book that I'm convinced I would hate now and have the urge to pick up whatever book it is to prove that I'm right. These particular books are from when I was still obsessed with the Young Adult genre which has a lot of atrocious content. Here's a few of them now.
1) Twilight by Stephenie Meyer
This is an obvious one to a lot of people. While I'm grateful to Stephenie Meyer and the Twilight Saga for getting me into reading, there is no denying that this book has a buttload of problems and no amount of vampire sparkles can gloss over them.
2) House of Night series by Kristin and P.C. Cast
Although I love that these books are written by a mother-daughter team, I can't help remembering that I had to stop halfway through the series because the books were such stinkers. They had no sense of continuity or sense and the heroine had a horde of boys trailing after her. Bleh.
3) Maximum Ride series by James Patterson
To be fair, these books were a big part of my childhood. However, they declined in quality as I get older and I feel like if I were to go back and re-read the first book, I wouldn't find it nearly as engaging as I did when I was young.
4) Gone series by Michael Grant
I remember having issues with the writing of this series right off the bat. I have no inkling of what made me give the first book five stars. If I re-read this book and the following, I think the rating would be a LOT lower.
5) Thirteen Reasons Why by Jay Asher
Probably the only item on this list that isn't a series. I think I was being kind when I gave this three stars - I absolutely hated it. As someone who deals with depression and suicidal ideation, I felt like the subject matter was romanticized, The focus was taken off of the girl who had killed herself and put more on the main character and how he felt about everything, then only alluded to the girl as a mystery for him to figure out. It made me feel icky the whole time I was reading it.