Wiktionary
quacky
a. 1 (context of a voice or sound English) That resembles the quack of a duck. 2 Fraudulent; characterised by or using the methods of quackery. 3 (context US of land or a crop English) Infested with quackgrass.
Usage examples of "quacky".
He was just as quacky as Donald Duck, but he was no more a murderer than was that excitable mallard.