"Is that bad?"
Translation:Ist das schlecht?
It is very unlikely that "böse" is the correct translation in this context. "böse" is referring to people with an evil nature, whereas "schlecht" describes things of bad quality or eligibility. In the sentence "Is THAT bad?" I assume an object, thing or circumstance is meant, but not a person.
Hope that helps :)
Edit: There is an additional meaning to "schlecht" - you can use it to describe a person. Then it basically has the meaning of "böse".