In the various discussions we've had here on this topic, there seems to be several approaches people tend to take:

1. Do it all as originally done, because it's history; explain as necessary so that the cultural context is taught as well.

2. Make minimal changes as you consider necessary, for the setting in which you will do them.

I think an additional consideration is this-- that in your setting, if you are teaching the songs to people who may or will learn them, don't pass on the offensive stuff and thereby perpetuate it in the culture. Teach them the history, yes-- sing it for them as originally done. But then teach them a better version for today, that they can pass along. Teach them to THINK about what they hear and sing, and make a way for them to wrestle with the question in a meaningful way.

~Susan