I scraped all of ours... tremendous difference - it looks SO much better.. but.. is labor intensive and makes THE biggest mess you've ever seen.. there are differing techniques I could advise on, if you get to that point.. What I will say, beforehand, which may affect your decision to do it: Do your ceilings before you do anything else.. Always work your way DOWN when doing lots of improvements.. so, ceilings first.. After you scrape your ceilings, I'd have a wall texture guy come and spray a light orange peel type texture on the ceiling.. its a VERY light texture, but hides the billions of imperfections.. Once sprayed you can paint the ceiling.. always get enough ceiling paint so that you'll have leftovers for touchups - or get a common brand/color that you can always find..
Friendship is like peeing your pants.. Everybody can see it, but only you can feel the warmth..