hey I just wanted to chime in on what your sweep said.
Maybe it's just my VC stove, but I disagree with him.
I used very well tested dry wood (<19%MC), and if I dont run my stove fairly hot, I can get my flue very dirty.
I had a 'creosote burn off' aka chimney fire about 3 weeks into burning only maybe 10 fires?  I was trying to run the stove as cool / long as I could to produce a long even amount of heat, and running it without a cat which helps burn up some of that smoke before it hits the flue.
So I set out to determine what my flue would look like after just a couple of burns running like this.  I should clarify, a burn to me is a day and night of burning.  Daytime usually run a bit hotter/quicker and night being at 400 or sub 400 STT.  At the time I didnt have a probe to check the cat area temps.  I was aiming for what a stove is supposed to be for, putting out heat - but trying to avoid too much heat too quickly resulting in a morning time chill.  ON both days I turned the air down too far, and still had 1/3to1/2 wood left in my stove in the morning, albeit it very blackened wood with black glass.
Pictured, are the results.  From the flue collar up.
 
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