I used to do whites in hot, towels in warm, everything else cold. I switched to cold for everything but whites (warm) and noted no difference in cleanliness. I line dry for teh most part-sun is a natural disinfectant. Used cotton diapers for the kids, and hung out, they were crystal white (done in warm also), no stains, clean and fresh. If you machine dry-that alone would kill any germs off.
I've always used cold water.
We always use cold