Obviously, among normalfags if you don't like something you just don't talk about, beyond a few extreme exceptions, like the sonic movie and shit
So the best way to do this would be really basic
To see how much people are focusing on adventure time in the earlier seasons versus how much they are in the later ones
So in the pic related you can see all the dates of all season premieres, starting with 5 labelled, and the series finale labelled in green
Now an important thing to note here is that. when people are interested in the start of season 2, 3, 4, 5, 6, or any season, its because of what they came before it, they can't know they like season 5 before it airs. So when they tune into something like say, the season 5 premiere, its because they enjoyed season 4, not because they enjoyed season 5. When a show is gaining viewers, its because it's been good enough to attract new people, and to have them promoting the show and tuning in.
And when a show is losing viewers, its because the show is making people, who were previously interested, and its losing fans faster than its gaining them, Something. obviously evident of a decline in quality
So why, why in the world, would Adventure Time, be losing so much interest, so gradually, over 5 seasons in a row, if everyone was loving it?
Maybe, just maybe, there was only a small demographic of people, who really enjoyed the new direction of the show, and maybe, they were very vocal about it, and maybe just maybe, criticizing a children's cartoon isn't something that gets published by industry press no matter how popular the opinion.