I removed all of the ceiling popcorn in our previous house and re-finished all the mud, then primed & painted over a smooth ceiling.
The ceiling popcorn had been absorbing the funk & smells of 30+ years of living & cigarette smoking, and was disgusting.
This house we've bought also has the popcorn, but it's just funky from living, as the previous owners were 7th Day Adventists, and totally non-smokers.
But I hate the stuff, so it will be my winter project to go room to room removing the popcorn, refinishing, and repainting.
But I prefer smooth, so needs a little extra work to get it there.
I might do a knock-down, if the wife will let me.
I hate sanding upside down with the arms up, too, Dez.
Effin' sucks, especially when you can see how much more you have left to do on the job.
Thank FSM for Union Breaks & good herbage.