Scotch guard may interfere with the natural dirt repelling qualities of the wool though. I tend to wash and try to get some lanolin back in, either through lanolinated wool wash or lanolin rinse/tabs.

I go for low agitation, cool temp, multiple washes when I'm being patient and don't want things to full. One wash if I'm being bad and impatient and dreading the onset of CADD before I do anything useful with it.