Not all of the Daedric quests are completely evil in their outcome. Meridia is downright benevolent, Sheogorath is kinda doing a good deed, Sanguine doesn't cause much harm unless you the character decide to be a dick to everyone, and even then it's mostly inconveniences. Azura's relic is completely neutral, and in fact defying a Daedra's will results in a more dangerous and evil artifact.
Calvicus Vile... That's an interesting one. You can argue that not helping Barbas at all and ingoring the quest is the best option. You keep Clavicus and Barbas separated, rendering him nearly powerless. But what if someone else comes along, decides to help Barbas, and claims the rueful axe? Clavicus Vile gains all his power back, but none of the restraint of Barbas. It might well be safer all around to help Barbas to curb Vile's power.
You can refuse to kill Silas, at which point he'll return to Dawnstar and keep the pieces of Mehrune's Razor locked away.
EDIT: I almost always play mage characters in Skyrim, and eventually gather quite a few powerful artifacts of a magical nature, Daedric and otherwise. As a part of my immersion, I either always carry powerful artifacts on me, lock them away and guarded by a housecarl, and when I eventually stumble upon Labyrinthia, I use the time displaced barrow and wooden mask to hide Daedric artifacts and Dragon Priest masks. Where better to hide them from thieves, warlocks, and Daedra-worshippers than outside of time?
How does that have any relevance to her quest in Skyrim? How can anyone who despises the Daedra, Daedra worshippers, or warlocks actually hold an act of destroying Daedra-worshippers by a daedra an example of how truly evil a daedra is? That doesn't make much sense to me.
The only good course of action is to help her, otherwise you're letting a necromancer prey off the soldiers of the war at the very doormat of Solitude.
The main Daedric quests nearly all my DBs do are those for Meridia (for Dawnbreaker) and Hermaeus Mora (for the Oghma Infinium). Maybe Sheogorath for the laughs as well. If I know a Daedric quest will require me to do some evil shit (Mephala, Molag Bal, Namira and Boethiah are the major ones), I either don't do the quest, or I do whatever it takes to fail the quest. As for Clavicus, when I did the quest, I returned the dog to him and just kept the Masque locked up in my chest.
This is an RP one I thought of today while playing my overly zealous holy warrior.
I just did Mephla's quest. Upon discovering that it was the Ebony Blade that was poisoning the kid's mind, I took the blade and stuck it in the cellar of my house to keep it from corrupting the weak minded (I need to keep an eye on my steward though!) I figure that it should be safe surrounded by all those shrines to the Divines. Technically I'm not doing her bidding, and the quest leaves my log. I'm planning to figure out some ritual to do that will destroy it, then use the disable command.
Forgive my confusion but this thread seems very contradicting to me. Anything associated with a Daedra is considered evil no matter which way you go about it as it is their nature. No matter how you go about it you're still doing their will so I fail to see if you despise the Daedra as so then why are you even considering doing their quest?