Another thing that happens with Spotify playlist is that someone will post something like:

"epic hip hop bangers"

Song 1-13 will indeed be epic hip hop bangers. Then song 14 is some random guy's track, which picks up the playlist momentum from its neighbors. Song 15-23 is epic bangers, then song 24. and on and on. The person who made the playlist is, of course, random guy or one of their friends.

That's why I typically only listen either to whole albums on spotify, or DJ sets on soundcloud or youtube. There are too many individual human beings out there with great taste to bother with the algorithmic stuff.