What do y'all think of hidden trophies?

To me, they feel kind of OP to discover if you're not a very motivated person, but I suppose that's who they're for. I did one of those trophies for Sonic Generations when I stumbled upon it online and it was to no-hit the final boss on hard mode with no add-ons (in game stuff) and I can't help but feel that there's no way I would have known that's the trophy.