One way to protect your nozzle from getting dirty is to wrap it in a cover, sock, sleeve or boot and prevent all the hot nasty stuff sticking to it. E3D released their silicone sock for Vulcano nozzles but someone found a way to make a DIY version.
Ubermeisters used 3d printed model of the nozzle and made a mold around it and than used some high temperature silicone mixture to produce the final cover. All steps are photographed in detail.
Here are the files and the instructions:
Build log gallery:
And here is the E3D sock: