It's become a bone of contention when she builds a fire when I'm home because it is very difficult for me to just sit there and let a smoky fire burn when I can fix it pretty easily. But if I fix it she gets upset with me because she thinks her fires are perfectly fine.
This is of course universal, and by no means limited to fires or spouses: " It's become a bone of contention when she (FILL IN THE BLANK) because it is very difficult for me to just sit there and let (FILL IN THE BLANK) when I can fix it. But if I fix it she gets upset with me because she thinks (FILL IN THE BLANK) is perfectly fine."
Unless (FILL IN THE BLANK) really IS causing serious harm to others, then (FILL IN THE BLANK) actually IS is perfectly fine. Most of our problems and disappointments in situations lie in our biased reactions to the situation rather than in the situation itself, which by any objective measure isn't really that much of a problem (certainly not compared to REAL problems).
You have a choice: be right, or be happy. So maybe just be grateful you have someone who can build an awful, wonderful, overly-smoky fire. Fortunately, you already know there is no good solution to this other than to just shut up and deal. When you stop reacting to the situation as though it was a problem, it ceases to be your problem (or hers, after she reacts to your reaction). It becomes just the harmless situation that it actually is, like any other harmless situation that needs no label of "good" or "bad."
However badly she "screws up" the fire, the end result is probably going to be hours of a nice, warm fire that burns itself out until someone builds the next nice, warm fire. How bad can it be? The only bad thing is the reaction, and the ill feelings that result.
(My wife, BTW, would laugh her head off reading this, since I micro-manage everything she does that is fire-related or wood-related, unless I make the effort to remove myself from the vicinity and let her be. As a friend always tells me: please, take my advice, I'm certainly not using it.)