These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Ass Pull: On a few occasions, the good and bad endings came out of nowhere.
Esoteric Happy Ending: Some of the good endings merely consisted in the main character surviving, or stopping the Big Bad temporally. Others were way too open and ambiguous.
Narm: Happens sometimes in some of the books, due a poor choice of words for the endings, weird descriptions and strange illustrations.
Nightmare Fuel: Many, many of the "death ending" illustrations, especially considering that these books were written for a young audience. As if the detailed description of your demise wasn't gruesome enough. A good sampling of some of them can be found here.