As long as the weather is crappy and they have access to the weather... they are going to look like it. I have a beautiful white silkie, all poofed and proud... but man, when it rains, she looks horrible. My polish are filthy right now too. Can't wait for good weather to get them bathed and brushed. (Yes, I did say brushed.)
Quite a few of my Silkies look like that. No matter what I do they seem to find water, and dirt. I can't wait till I can try my new chicken water nipples, but I have to wait till the weather stops freezing. Hopefully, that will do the trick. Otherwise, to get the Silkie to look nice, I find a bath is necessary. And what really gets them to fluff up, is the blow drier.