The Loathsome Dung Eater guides the player to the worst ending in Elden Ring, and there is absolutely no reason for the player to follow him to it. The game goes out of its way to let the player know that following Dung Eater is a bad idea, and they would be wise to listen. Dung Eater's ending is not only horrible for the Lands Between, but it's also completely pointless.
[Warning: The following article contains spoilers for Elden Ring.]
There are several endings in Elden Ring, most of which are provided by various NPCs that the player will meet in their travels. Most of these characters, such as Ranni and Goldmask, have great importance in the world. However, Dung Eater is a reviled serial killer, so him having an ending route feels quite strange. Indeed, Dung Eater's questline turns out to be as vile as the man himself, and as it is almost definitely the worst ending in Elden Ring, it will make one consider if it was really worth the time invested to reach it.
Dung Eater's ending, the Blessing of Despair, requires the player to finish his questline by giving him Seedbed Curses until he dies and provides a rune that will spread his curse throughout the Lands Between for what will likely be an eternity. While most of the game's endings are ambiguous to a degree, this alongside the Lord of Frenzied Flame ending is one of the only purely negative ones. It's an unsurprisingly bad end, considering who is offering it. If one is willing to follow Dung Eater's Elden Ring questline, it will have to be against every warning sign possible.
Dung Eater's Ending In Elden Ring Is Not Rewarding At All
The game makes no attempt to hide that Dung Eater is not to be trusted, and following his questline is a bad idea. Every character who speaks of him shows nothing but absolute contempt for his very existence. His first appearance is in a room full of corpses, and if one follows his questline, he can even kill the rather likable Big Boggart for no reason. Dung Eater himself does nothing to act trustworthy, being fanatical about murder and wanting to spread his horrific curse as far as he can. Even collecting the Seedbed Curses forces you to visit Dung Eater's horrific murder scenes. There is not a single moment where the game will let you forget that Dung Eater is Elden Ring's most evil character.
Dung Eater's ending is not only useless in the universe of Elden Ring, but to players as well. Many games with multiple endings will have achievements associated with the various endings, and Elden Ring is no exception. However, while there is an achievement for becoming Elden Lord, which several endings involve, there is no specific achievement associated with Dung Eater's ending. In fact, nothing that Dung Eater requires the player to do, from interacting with him to collecting Seedbed Curses, will reward an achievement. As a result, players who seek to finish 100% of the game's achievements can completely ignore what Dung Eater asks of them and still complete the game's achievement list. This means that players don't have to take on the arduous task of finding five Seedbed Curses in Elden Ring.
Dung Eater is someone who should be avoided no matter what, and Elden Ring itself seems to enforce that idea. From having every character who knows of him show utter contempt or fear, to offering no rewards for his sidequest, it's as though the game wants to keep the player from having any incentive to work with him. Considering his role as the most evil being in Elden Ring, it's easy to see why.