The opposite would be to taste terrible or taste awful (there is no specific word that means tastes really bad).
Some other possibilities are unpalatable, unsavory, or unappetizing.
The absence of taste could be another alternative: bland, tasteless, or flavorless.
Chat with our AI personalities
Distasteful is one opposite of delicious.
Some other opposites are disgusting, bad, bland, disagreeable, tasteless, horrible, repulsive unappetising and unsavoury.