Blood C is not a trainwreck. The writers clearly planned for the show to go a certain manner from the outset, they weren't just making stuff up as they went along for extra shock value.
A trainwreck is the kind of thing which lots of people watch because it's hard to turn your head away - but Blood C opened with a series of boring, formulaic episodes which is exactly where most people dropped it. Very few people seemed to get to the end of the show, and I know that many people here wouldn't have picked it up without duckroll bringing it up.
I know that practically no-one watched that show because there were very, very few blog posts about the ending. If you've seen how the show ends, you'd have to write something fairly substantial about it, so I can tell many people never even got that far.