Up here in my part of the Great White North (Montreal) any kind of textured finish is only used in lower-end housing. When we built new out in the country, there was no question about texture - all walls and ceilings are level 5 smooth. Properly primed and painted there are no imperfections that can be seen. I'm in the process of a large DIY remodel of a 109 year old house (in town) and all the drywall I'm putting up (walls and ceilings) will be smooth. To my eyes, texture (such as popcorn and orange peel) has that "cheap motel" look and screams "lack of skill". Any idiot can slap up drywall and spray it with a machine to cover the poor quality workmanship. I'm originally from the UK where the norm is to use real plaster (actually it's a lot faster to do than taping and mudding drywall). Textured finishes were popular in the 1970s (particularly on ceilings) but they looked like crap when done DIY and again were just to make up for a lack of skill. Otherwise smooth finish was the norm there too. When I see anything else but a smooth finish, it just makes me think of this! Of course, if all you're used to is seeing texture, then smooth probably looks strange. Paul in Montreal.

GreenDesigns, thanks for your input. I am not plastering, just skim coating a thin joint compound over the entire drywall surface to even out the contrasting textures between the dry wall paper and the smoother areas of joint compound at the seams and at the screw sites. Maybe "skim coat" is the wrong term, or used loosely in this application. I have read multiple opinions on the use of moisture resistant wall boards. Opinions are very divided. I was miss leading in my OP in that this is a moist room, as this room has never gotten steamy in the 22 years we've lived here and there was no fan. There is no shower, just a tub. But, because this is a bathroom I can assume there is more moister than, say, the living room. What I have read regarding regular drywall is that if it is used in the non wet areas of the bathroom it really is more important to have a proper primer and paint installation to protect the wall system. When my kitchen was done last year the drywallers did skim coat my walls, I just wasn't there to see how they did it. I have watched the USG video and it is straight forward enough. I have attached a link below. Lastly, to provide some context, this room is not our main bath, that is why there is no shower. This bathroom is next to my kitchen. The bathroom is really a combo utility room/bathroom for our farm house. Here is a link that might be useful: US Gypsum video on level 5 finish.

Since you asked, I just completed an exhaustive renovation of my dining room ceiling where I removed the popcorn texture and added faux beams and custom crown molding (see the link). So, as to your question, "how much 'perfection' should I expect in a smoothed ceiling finish?" Remember you are talking about the ceiling and few people really notice/view/stare at what is going on with a ceiling. In my renovation, there are many areas where I did not sand the ceiling perfectly smooth after I scraped it. Flat paint works wonders for hinding all of them. What I would expect is that any imperfections not be noticable to the average guest who visits your home. How much wave is present? Fixing that would likely involve removing the sheetrock and sistering framing to the existing rafters to make them straight, then replacement of the sheetrock, etc. - a significant job in my mind. It just depends on what makes you happy and how much trouble you want to go to fix the concern you have. Here is a link that might be useful: Custom Crown/Faux Beams

Yes, the blocked vent is in this bathroom. WHY WOULD ANYONE IN WISCONSIN TILE A BATHROOM AND COVER THE HEAT SOURCE? Good grief. I washed part of a wall and got the paste off easily with vinegar and tea tree oil, the mold appears about 50% lighter. With no trim, floor or fixtures, it seems a good time to just tear out the drywall. At least I can raise the light fixture to an appropriate height and get rid of the recessed t.p. holder too. Maybe add sound insulation. So much for a mini reno.