@SotiCoto, Yes those are all valid solutions. However, certain people like myself (I don't know, maybe i'm in the minority?) have too high of a level of OCD for any of those solutions to be an easy fix.
I'm obsessive-compulsive too. Apparently just about different things than you are though. Like the way my brain practically starts bleeding if I try wearing an incomplete armour / clothing set, and if I make an enchanted set they all have to have themed names and sit next to each other in the inventory, or I can't use them.
SOLUTION 1: Nearly impossible because every time you open up the quest window it's there. The MISC. quest group is there in plain sight and will always be in plain sight, unable to ignore it. I don't know how much you know about OCD but it's an uncontrollable psychological urge, for me to keep things organized and tidy. It's not just a simple little desire, it's a necessity.
I know plenty... in a first-hand sort of sense.
My first port of call is "Ignore the Misc quests, for Misc means Trash Bin in Skyrim".
I don't like having incomplete quests either, but I'm TOTALLY able to ignore them if they're Misc.
SOLUTION 2: I have done this and sometimes it works. The reason I say only sometimes is because I often forget who that person was and engage them in conversation hours or days later to be tricked into obtaining the quest in my quest window again. Another thing that happens is after i'v already begun conversation with them my curiosity bugs the crap out of me about it because I always wonder what his or her deal is. I often remedy this by going through the whole conversation with that NPC, obtain the quest, then reload a saved game from before I met them. To have to constantly reload save games and make sure to save every five minutes just so you can do that doesn't seem right to me.
Forget who it was? The game is mostly quite neatly arranged. The NPCs each have their fixed place, fixed movement schedule... very nice, orderly and predictable. That includes most quest-givers too.
Perhaps I should clarify that I've been through the game a few times now and done most of the quests with one character or other.... so I don't get any bouts of insatiable curiosity.
SOLUTION 3: This would work too, yes, except that I may want to do the quest at another time. This is why I mentioned "temporarily " being able to delete the quest from your quest log.
That is kinda what the quest log is for: Quests you might want to do later.
Isn't as nice as a quest journal like the previous games had... but it serves its purpose.
My whole reason for explaining this is because there seems to be many people out there like yourself who don't seem to understand why the many people i'v seen out there like myself can't just do one or any of those three solutions you listed and stop complaining. Hopefully my explanation will help others to understand. And just to be clear, obviously I still play Skyrim; This isn't a game breaking "problem" (for me at least), but a very nasty annoyance indeed.
I don't think Skyrim was made with obsessive compulsives in mind.
I don't think most games are... besides Pokémon, obviously.
I'm just glad I'm not bugged by it the way you are.
I'm far more bothered about the lack of all the various things I loved in Morrowind.... including some I deemed essential....