If you are using a cheep detergent that won't dissolve in cold water, you will need to use warm or hot.
If you buy a quality detergent (Tide etc) cold wash should work.
I tell people out here in the Northwest where we have soft water to only use 1/3 to 1/4 of a scoop. (what ever the size scoop that comes with the package)
We use 1/4 scoop of the Kirkland powder detergent and the washer doesn't stink and I get clean clothes. I have seen the inside of the tub when I did a bearing job on the machine and it was free of soap scum.