keione ahnung aber der spruch heißt nicht "nett..." sonder "Ganz Nett ist der kleine Bruder von Scheiße!"

Hat denn nach knapp 2 Jahren jemand eine Ideen

"that's nice" is just another way of saying "it sucks/stinks."

e.g.

The German idiom is actually a metaphor, perhaps even a simile because of the "younger relation" essentially functioning as "like." Saying something is nice when it is not really all that nice (giving a flattering "nice" assessment) is the younger sister (or younger brother) of just saying something is bad point blank.

In other words "Nice" is "closely related" and thus nearly like saying something is really bad.