WHY DOES MY GLASS GET SO DIRTY?

Glass should be clean enough to view the fire easily. This is accomplished by feeding primary combustion air into the fire from a slot running across the top of the glass just inside the door opening. The flow of air "washes" the glass unless one of the following occurs:

Air flows into the stove to feed the fire from another source other than the air wash. Most common is the door or glass seal but it could be any joint in the main panels low in the stove (including the air channels inside the combustion chamber).
Poor draft: the air flow is very poor and not providing enough air to "wash" the glass especially on a full load.
Burning unseasoned wood.
Wood is too dry which causes too many particulates to be emitted rapidly.