This is a really interesting thread to read! And I want to share my own experience.
I grew up with cold water washing for everything except whites that always got hot 60°C washing. Mind that my parents moved to the south and even in winter water temperature never is under 14-15°C (58-59°F), when I moved to the north again for my studies I kept this same habit. At first I didn't notice anything but after a few months my dark towels and in general all the fabrics that were thick started developing the strange smell I will always associate to bad washing. I didn't understand what it was at first because the machine never smelled as I kept on doing regular 60°C washes for whites. I asked my father and he advised to wash darks at at least 30°C and so I did. In just a few washes the smell went away for good and never returned, until I changed house and got a new washing machine, my current Whirlpool crap that can't wash, rinse or spin properly. This machine has only 3 cycles at 30°C; delicates 30°C, 30 minutes and hand wash. The 30 minutes cycle is just too short and delicates doesn't tumble enough to get stuff clean (plus no spins between rinses), hand wash, tumbles like 3 times in all the wash cycle so I don't consider it. I used the delicates 30°C and then, after the disappointing results I went to "cottons 40°C" that become my everyday cycle, now, everything comes out clean but I can't use powder otherwise colours will fade so I begun using liquids for darks and powder for whites. Before that I only used powder, even in cold water and the results were great.
The reason is that cold water here is cold, same as outside temperature and the detergent wasn't acting as it was intended. In my current flat, with underfloor heating, cold water on the contrary is never UNDER 20°C and I could continue with cold water washing for darks but the machine is such a POS that I can't do it without results suffering (and besides it doesn't have a cold water wash!).
So my final note is that those that wash in cold water and are OK with it have the blessing of cold water that isn't that cold, a good detergent and a nice machine that does the job.
On another note, I'm not a germophobic at all and on top of that I avoid buying stuff containing germicides as I believe that all that stuff dumped in the environment does no good and creates resistant stains of bacteria more and more difficult to defeat. Laundry never will be sterile or better, it can be but as soon as you take it out of the washing machine it gets in contact with the billions of germs in the air and those on your hands, so I really don't see the point in all that market.
Laundry should be clean, let leave "sterile" to the hospitals.
Oh, and I hate to prewash and do stain spotting games so even very dirty stuff goes in the washer without me touching them, cold water, even with the best detergent can't shift ragù-sauce stains from a white shirt, 60°C can do it easily and without an abuse of chemicals.
I wonder in Japan where I've been told that hot water washing simply doesn't exist how they deal with such stains, how the laundry habits are and on top, what there is in those detergents, I guess they must be stronger than European ones for sure!
Does anybody know more than me?
