Mike can you talk a little more about stoves that were "burned dirty" and firing the soot and how to avoid all of that? This is my second year with a Mt Vernon, and I notice that every time I clean my stove (which is every 7-10 days in burning season) that I need to clean the glass. That makes me think I'm not burning hot enough or long enough. With the Mt Vernon there's so many settings that its difficult to know what settings will allow me to burn hot enough to avoid what you are talking about.
understand that when stoves are designed, they are built with specific spaces in the airflow chambers (the intake, firebox and exhaust/ heat exchange pathways). as ash accumulates in the unit with use this starts to affect the volume of air that is able to flow through these spaces. at some point a tipping point is reached where the air volume is no longer sufficient to completely burn away the combustible materials, while it will still support a fire the fire is only attaining a partial percentage of combustion. the "soot" that coats the combustion and exhaust areas of stoves and your pipes as well is simply unburned fuel (similar to ceosote in a bad burning woodstove chimney) as this us really the same stuff you are feeding the unit once the stove is cleaned out enough to get that airflow back its possible to reignite this unburned fuel and have it literally burn off from the surfaces its clinging to.
as for your glass, its not unexpected to have the glass get ashed over somewhat after several days, note that the slowing airflow i described above even though its not bad enough yet to leave soot coating, it is going to slow the air down somewhat and that affects the airwash system in most all pelet stoves, especially since very little of the total amount of airflow is relegated to airwash duty as most is channelled for combustion, smaller openings provide more resistance to flow, air wants to move through the path of least resistance in a negative pressure (direct vent) system. so, in a nutshell, airwash is one of the first things that start to show buildup.
now burning hotter may help depending on the makeup of the ash, if its light gray or brownish its generally just ash, if its dark charcoal gray or black, its unburned and running hoter may clean that up some, note also that higher RPM's are present in high burn so air velocity would improve a bit so the glass may stay a bit cleaner longer with this working for you as well.
finally, if the coating is like in the picture above , the other poster put up, its not abuse, but his stove is probably in need of cleaning by the time it gets that heavy. pay attention to the color of the stuff on the glass the lighter in color it is the more completely burned it is. also, keep a mental note as to if it seems to build up quicker than it has been, this is an indication that you may be building up in an area that is not part of your regular cleaning, check the vent pipe and maybe go back over your manual carefully to ensure that there isnt a spot you may have overlooked.
BTW the Mt Vernon is a great stove. hopefully some of the members who have that brand or unit can chime in and help you a bit with the settings. i know pellet stoves pretty well in general terms, my stoves i know intimately, but other brands im just not "up on" the control sets to really be able to advise you in anything other than general terms.
hope this helps ya!