Irregardless doesn't ping with me as a crime. It's sort of like how "flammable" and "inflammable" both work fine. I know it's a double-negative, but it's usage is too widespread — and it's sort fun and vernacular, which I always appreciate — for it to be flat-out wrong.

This language writer guy agrees with me: http://www.huffingtonpost.com/jonathon-owen/yes-irregardless-is-a-wor_b_4434749.html