Could vary. I always believed that there is good grinding, while there is bad ones. Usually, it's the commitment and what you get for doing it in return. If what you get isn't worth the grind, I consider it as bad grinding. If what you get helps you in the long run and you found enjoyment with what you got, I consider it as good grinding.
eh, that's kinda true, but it's dullness can be mitigated in various ways, you can have a "skip fluff animation and get straight to the point" button like your Hyperdimension Neptunia or Demon Gaze, or you can have the grind be more varied and interesting like your Zelda BoTW. While i don't think grinding is inherently bad, any step to make it not feel like a slog is gladly welcome
Pretty much good grinding and bad ones yeah. If it's a slog, could be labeled as a bad one. But there has to be something worth it in the end to make that grind to begin with, which is what the grind normally aims for.
If it's a slog and getting something that's hardly worth it, I find that to be pretty bad.