It really depends on the game. I don't mind some extra padding if it's optional, there's some sort of tangible reward at the end or it's relatively painless. Like all of the insane post-game DLC content in Fire Emblem Awakening, which is hard enough that things can still go poorly, even with a maxed-out team. That stuff is sort of cathartic in its mindlessness, at least in short bursts.
That being said, man, MAN do I hate it when grinding is not only obligatory, but a constant requirement to make any sort of progress. The DS version of Final Fantasy III is bastard hard, not because of any sort of strategically demanding combat scenarios, but mostly because their numbers are always markedly higher than your numbers, so you have to grind random encounters until you gain enough levels to not die super quickly.
The only game I can think of in which I really enjoy grinding is the Persona series because the core combat in those games is so solid and enemies are relatively quick to beat after you discover their weaknesses. Most importantly, though, it's because unlike most games there is a direct incentive (fusing a new persona/learning a new spell) for each level you go up. In most RPGs you only get a new ability every few levels, but Persona always gives you something new to fuse.
Oh, I guess Fire Emblem, too. While actual levels aren't quite as important as in Persona, characters generally level up pretty quickly and the gameplay is so solid in that series I tend not to mind having to go through a few grind maps.
2 games stand out to me as far as grinding. Dragon Warrior 2, which had crazy amounts of mandatory grinding before you could handle the next dungeon, as limited by your small inventory and the cost of buying new equipment. By the time they got to DQ4 and 5 there was a heck of a lot more time devoted to story, more puzzle elements in many of the dungeons, and other elements to distract you from the grind. I liked the classic balance, though.
And the other game was Ragnarok Online, which was the old style of MMO where leveling up was the whole game, more or less. Even after they added PVP, most people still weren't max. Reaching max level was an event that, by the time you got there, you'd have lots of friends from the time you spent partying that would all come to watch you finally hit 99.
I loved both of those. I have never disliked a game for containing too much grinding. And when the grinding itself isn't compelling enough, I just throw on a podcast while I do it.
A purposeless poll when it entirely depends on how much you enjoy the gameplay. Varies so wildly from game to game. For some games this is everything (NBA 2K for example, which I pay every other day or so, basically is just a season grind, like the real sport).