"Dieser Hund ist nicht nett!"

Translation: This dog is not nice!

[Mwalek]

Does nett mean the dog is not well behaved or does it mean it is not a good breed (for example) and you don't like it? Or it can it be both?

[TheDreadfulGuy]

Ja, dieser Hund ist nicht nett, weil er sehr böse ist!

[MortiBiRD]

bad doggo is no good boy

[milling1]

He's not a good boi :(