He would never accept any responsibility you attempted to give him.
I think he would, just to appease you for the time being. The moment you walked away, he’d completely forget about whatever it was he promised.
Difference based on different definitions of “incompetence”, one suspects. And it seems to me that characters are competent in some areas but not others. E.g., Tom Bombadil is irresponsible, but not necessarily incompetent. In his own realm – dealing with the trees and forest, say – he was undoubtedly competent.
Thorin was competent in terms of charaismatic leadership, but not as a planner or strategizer; he relied on others to do that for him. Sauron was certainly competent as a wizard, but not as a military leader or political planner (although, to what extent he relied on Sauron’s [mis]information is not clear.)
The most incompetent seems to me to be Denethor, and certainly Denethor of the movies. His job was steward, and he failed in almost every way imaginable.
He doesn’t seem like the appeasing type to me. He’s a good host in the rare times he has visitors, but that’s about it.
I’ve mentioned before that whenever we actually see Tom in action, he seems to have a perfectly firm grasp of what’s going on as sure as he understands mortal concerns: he makes his debut by rescuing trapped hobbits after reassuring folks that he knows how to get the job done, exits the story by equipping our heroes with a good deal of useful stuff, and in between teaches 'em how to summon him if they should ever need more assistance (which they of course do, whereupon he shows up to supply the necessary help). The guy who asks Frodo a lot of relevant questions isn’t detached or even mysterious when explaining that he already knew the hobbits were on their way for to add that he’s been waiting for 'em: he only ever strikes me as practical, to be honest.
Various other characters talk smack about him when he’s not around, but IMHO that’s kinda weak compared to the folks being put up for consideration in this thread.
Perhaps not incompetent, but Celeborn is always referred to as “the wisest of the Galadrim”. I always thought that this spoke poorly of the intellect of the Galadrim, as Celeborn seems to be distinctly lacking in the smarts department.
How about Radagast? I don’t know if was incompetent, since I don’t know what he was supposed to be competent at. He bumblingly lured Gandalf into Saruman’s clutches, and was MIA for the entire War of the Ring. His only saving grace was that he IM’d Gwaihir, who eventually rescued Gandalf from Orthanc, through no plan of Radaghast’s.
I think Thorin and the foolish Dwarves willing to follow him were indeed the most incompetent. Let’s give **Bombur **some credit here for his idiocy. What was he thinking? There is no way he should have gone and he caused many problems on the way. He was unfit physically and mentally for such a Quest.
I need to clarify this point as it bugs me. Meriadoc was actually very competent. He also was not the equivalent of a teen. He was 36 I believe when he made the plans to spy on Frodo and prevent him from slipping away. When he made the plans for having Frodo try to quietly move to Buckland first. He was ready with Ponies and the Ferry. As we know, 33 is pretty much the equivalent of 21.
Throughout the book he used his head. At Rivendell he studied the maps. He listened and he learned more but after Frodo he was a most outstanding Hobbit and of course showed bravery against the Witch King that very few could have matched.
It was to Frodo’s misfortune that Merry was not in the Prancing Pony when Pippin, the great fool of a Took, started to put them in jeopardy and Frodo finished the act on a grand note. Merry might have cut that off.
Now Pippin was only 28 of course. He was basically a teen. He mostly caused problems but did slowly grow during the war.
Denethor was not incompetent until after his brain was addled and rattled by Sauron through an unwise use of the Palantir. But remember in his youth he was a fair rival to Aragorn himself when Aragorn was in the guise of Thorongil. He was very strong willed and actually could not be corrupted by Sauron but only driven mad with despair. He managed to strengthen Gondor during his reign leading up to the war.
Yeah, some of the responsibility must fall on the wizard who thought Butterbur-post was a smart way to deliver an important message.
I think an OP nod has to go to Sauron. Putting that much of ones power into an obvious-inaccessible-focus rather smacks of min-maxing with insufficient grasp of the consequences. 
Morgoth would undoubtedly have been far more successful overall if he hadn’t wasted so much of his power to merely possess a couple Silmarils. Also trusting Ungoliant was a pretty stupid idea, not to mention consistently underestimating the Noldor. Sure, he trampled them nearly into oblivion eventually, but often at an enormous cost of spent power and energy of his own. He didn’t believe the Valar would ever come to the aid of Middle Earth, and that was the final blunder. He had spent to much of his own power at that point to remotely hold his own, as he had in the past, and his minions were simply outclassed. Embarrassing, really.
Doesn’t this make Saruman’s blunders look even worse?
Bombur and Radagast are up there in my book. Now, they may have suffered from bad press and selective reporting, but as presented, anything they did which was beneficial was rather due to accident.
Mîm didn’t have much going for him, either.
The trolls that were too dimwitted to remember to go inside when the sun came out deserve at least an honorable mention in the incompetence category.
Saruman certainly doesn’t look in the running for any “Evil Overlord of the Year” award… but his goal of grabbing the ring into which Sauron had perhaps unwisely invested so much power wasn’t necessarily an incompetent idea (even if not a good idea).
No calling them trolls outside the Pit.
There was that retarded fellow that would go on singing songs at the slightest pretexts. Tom Bombadil, he was called.
I dont know if he was the most incompetent, but if I had to personally kill one of Tolkien’s character by use of a blunt weapon, that would be Tom Bombadil.
This aint the Wizard of Oz, asshole, just because the guys you’re traveling with look like munchkins doesnt mean you have to start a singing act every fucking two seconds, for Christ’s sake.
Why pick on Tom for the singing? I don’t think there’s a single chapter in The Hobbit or The Lord of the Rings that doesn’t have at least one song or poem. If Tolkien had written the movie scripts, it’d be a musical.
Manwe, for just sitting there and brooding when he should’ve been out there kicking evil ass, and for being so totally fooled by Morgoth “I’ve seen the light and have now totally reformed myself, yessiree!” the Big Fat Liar.
Let’s throw in another candidate: Grima Wormtongue. Among other accomplishments, believes he can take on Gandalf in a contest of who can be more pursuasive with Theoden. Does not have the sense to leave town quickly when observing that Gandalf has a bad-ass Ranger, a bad-ass Dwarf, and a bad-ass Elf as wingers (currently unarmed, but for how long?), possibly overlooking that Gandalf is indeed armed with a wizard’s preferred piece, his staff. Eventually is pursuaded to leave town, runs into yet another demonstrated bad-ass, Treebeard, standing in the demolished grounds outside of Orthanc, and still believes his best chance is inside.
Later, while inside, grabs the first heavy thing he can find to throw, an orb that must have been pulsing with magical power like little else, and figures that the orb will make a good rock for chucking out the window.
Finally gets pushed over the edge to do what would have made so much more sense earlier, lodging a blade into his employer, Saruman. Even then, picked the wrong time for it and never got to enjoy any retirement benefits.
You can get into an unresolvable argument about both Saruman and Denethor because it comes down to unknowable questions about the extent of personal responsibility in the face of the power of Sauron and the Palantir. Can we know how feasible it was to resist the pull? Without resolving that, you can’t resolve whether Saruman and Denethor were fools or unwilling victims who fought with every ounce of their mental strength, can you?