Smoke smell in the room...
So many opinions, and seeming contradictions… But no, it all makes sense, as long as we have perfect understanding, which none of us has.
Is sufficient draft essential to good operation of the stove? Yes.
Does sufficient draft solve all problems of smoke smell in the room? No.
Some folks say that adequate chimney draft will solve the problem of smoke smell coming into the room, while others say that installing a new chimney adapter or redoing the door gasket fixed the problem in their case.
Why is it so confusing? Because we are not giving due consideration to the effects of turbulence in the system. Each stove system is unique. Turbulence is created whenever there is something that disrupts the smooth flow of air up and out the chimney. Start with the design of the woodstove itself. And with every fire, there is a slightly different configuration of logs in the stove, creating different patterns of air flow within the stove and up through the bypass and/or catalytic burner (you can often see this when you first shut the bypass, or adjust the damper down). Any roughness, sharp edge or anything that causes a change in direction causes some turbulence in the chimney system.
Whenever there is turbulence in a system, by definition it creates pressure differentials within the system. We take advantage of this with the design of an airplane wing, which causes lower pressure on the upper side of the wing, and hence a lifting force that enables planes to fly.
Turbulence can cause powerful eddies, rotors and other currents that, even if small, are greater than the air pressure differences between stove, chimney, room or outside air. In other words, air can get forced where we would not expect it if only considering the more obvious effects of chimney draft.
So the first rule, if at all possible: Make sure your chimney has sufficient draft. In the case of BK stoves, that means follow their recommendations of 15' chimney height (plus 1' chimney for every bend in the system – I haven't seen this in their literature, but that is what BKVP and others have said). Having sufficient draft wards off a number of possible stove problems, not just smoke smell in the room, so if you provide sufficient draft everything else should be easier, for the most part.
If sufficient draft does not solve the problem, then look more closely at your stove. This includes the door gasket, the adapter between stovetop and stovepipe, and any other rough edge, gaps or loose fitting pieces in the system.