I can definitely tell the difference. The Last of Us Remaster was a great tool in this regard, letting you switch frame rates at will - going 60 to 30 is horrific, while 30 to 60 looks bizarre. I also noticed that if I switched to 30 fps before entering photo mode (for more detail), I would sometimes forget to switch back to 60 afterwards and not realize it for hours.

Frame rate only really reared its head as a concern for me last gen, where I realized sub-30 looked atrocious, just as bad as screen tear or frame rate jumping up sporadically. Locked 30 or 60 is my preference (though inFamous SS did alright unlocked).

Side by side, yes.

I can also see drops, but no I wouldn't be able to tell you if a game is running in 30fps or 60fps off the bat in most cases

Everyone can. Those who say they can't never honestly tried or are lying.

Yes, but doesnt mean the tradeoff is worth it

Yes and easily.

A good game to try is TLOUR... toggle 30 and 60 fps to be amazed.

So is any game which switches to 30fps for cutscenes and is otherwise unlocked.

Yes I can but I don't feel that it is necessary if 60 fps will downgrade other aspects of the game such as the graphics.

Yes I can. It's very easy to see the smoothness and fluidity and I notice it in games.

Lol.

Obviosuly it's the one on left.  Just look at how much much more fluid thier swords swings are.

Depends on the genre, input method (gamepad or mouse) and art style.

Many games are okay in locked 30 fps, even if I can see the difference to 60 fps. Some fast games on PC I play on my 120hz-display, because even 17 ms (60hz/fps) feel too unresponsive.

What I absolutely hate are 30fps-games with slowdowns to 20 - 25 fps.

yes, 60fps definitely is better but 30fps is still acceptable as a minimum require...