[jeffchien]

Anime has had no shortage of adaptations disrespectful of the original. Most of the time it's due to not having enough source material like HBO GoT, which somehow sent Fullmetal Alchemist to 1920s Germany in the first adaptation's movie. But sometimes you get people like Bokurano's director who straight up said he hated the manga.

[least]

Fullmetal Alchemist and its movie are both excellent, though, even though they it's vastly different from the source (and of course, the more faithful adaption in Fullmetal Alchemist: Brotherhood).

I think the Lord of the Rings trilogy is also quite good, even though it does stray quite a bit from the books, omissions aside.

It's really hard to make good media and I haven't found any reliable indicators hinting at whether an adaptation will be good or not. I found The Hobbit trilogy to be laborious despite having Peter Jackson at the helm of it as well. Though in that case, maybe the source material itself is the issue.

[pnt12]

LOTR was a work of passion , The Hobbit was a mess.

With The Hobit , there was a change in directors (originally Guillermo del Toro) and lots of studio meddling (eg pushing for 3 movies when the original is a 200 pages book, inclusion of LOTR actors for wider appeal).

I think Peter Jackson was brought in to try to salvage what he could.

[xoxxala]

It also happens sometimes when anime looks to western media. "Tales from Earthsea" and "Lensmen" are notoriously bad adaptations.