Whether I sing something that might be considered "Objectionable" depends a good deal on my own comfort level--how comfortable I am personally with the message and intent of the song, and how comfortable I am with a given audience. For example, I love the Leon Rosselson Song, "Stand Up For Judas". I am perfectly comfortable with singing that song for myself, and maybe I would be comfortable in a song circle situation among people I know. However, to sing it in front of a larger audience--well, I'm simply not confortable with that. Perhaps I'm just a wimp! Or maybe I'm just overly sensitive to other people's responses.
The irony is, I believe in applying a little 'shock therepy' to audiences once in a while (I just don't seem to have the gumption to do it that often myself). I really admire other performers and artists who can do it and don't seem to mind the controversy they may start. Personally, when I am faced with something that is objectionable,I try to either take it with a grain of salt, or, if I am unsucessful, I try to learn why it makes me so upset.
Sometimes I categorize something--whether it be a movie, a song, a play, or a piece of art--as 'good' simply because it succeeds in provoking me. Of course, sometimes complete and utter trash can be provocative.
Great discussion, by the by.