I don't care much for songs that are sung with the intention to hurt or offend (and are extremely simplistic about it, too), like pretty much anything the Grehan Sisters sang.

On the same vein a very vile old song is the Orange Flute, God Save the King/Queen as well.

I know that with 'There Were Roses' (have only ever heard Tommy Sands) I just feel very ill after hearing it.

A song I would not listen to is The Well Below the Valley (though I admire Planxty's guts in recording that)

I like what Martin Carthy said about the song Prince Heathen, that the first time he read it he shook with rage, but after dropping the last line, he sings it to show man's cruelty to man.

Editing old songs because the sentiment might offend is very wrong. If you want to sing your own version without whatever offends you, thats different.