I have around 1200 ebooks in Calibre; around 300 I downloaded on purpose and the rest came in large batches. I have these two groups separated out. I'm pretty sure I've never read one from the batch group that was close to good. The vast majority of books are crap and if you pick at random you're going to pick crap.

Most of my batch books are from Standard Ebooks which, while a noble project, has a serious addiction to publishing dreck no one should waste time reading.