For me, it depends on the game.
I don't particularly mind grinding unless the battle system is boring, or if the encounter rate is really high (early FFs, I'm looking at you), so I constantly feel like I'm being forced into battle. In that case, grinding gets old really fast. If the battle system is fun or interesting though, it's usually pretty enjoyable. Chrono Trigger, Persona, FFXIII, and other games like that are fine, and I didn't mind grinding at all.
Also, if you can choose when you want to grind, it's not so bad. Some games where you feel like you can't progress until you get to certain level or have a certain skill though, that's pretty irritating.
Grinding is only a slog if it's tedious, in my opinion.