I can't call the following riddle a standard one with a certain answer but it's not that bad.
A native speaker said to me that he can't get "it's not that bad" part. Is it ambiguous? Maybe I should have said "it's is not too bad", but in general I use "not that bad" after I have criticized something and I want to make the situation better. For example, "her cooking isn't good, but it's not that bad, it's worth to taste....".
If it is an improper usage, then what can I say instead?