I don't think there's much wrong with the 'Frogs' tagline - it knows what it is. Self-aware. To me a bad tagline is something which aims to sound cool or profound and ends up just sounding dull, silly or cloying.
I remember seeing a film students 'trailer' for an adaptation of Blood Meridian, the tagline said:
'Every man has a scalp'
The trailer itself was pretty cool. All dark fading in and out, knives being sharpened, cowboy hats, hair being pulled, etc. Then... 'Every man has a scalp'. It just captured nothing of the tone of the novel or the potential film.
'Every man has a scalp'.
Well... yeah, I know. It's on their head.
They have shoulders, too.