The walls above my shower have been flaking for years. I'm now repainting, & scraped off the flakey area to find green board underneath, some of which is brown in places. Do I sand & use a bathroom primer recommended by the paint store? How much funky paint should I remove? I got all the crinkly bits & expanded the scraped areas so they made ovals instead of separate dots. Now what? Any suggestions would be appreciated.

It all needs to come out and be replaced with paperless sheetrock after checking for mold and treating if there is.
Green board would be green or light blue not brown. Brown sounds like mold to me.

The paint is peeling because of excessive moisture in the bath and lack of proper ventilation and insulation above causing condensation to form.

You need to scrape the ceiling completely. Prime it with two coats of Zinzer anti-microbal paint. Let dry and then paint with good quality paint over the prime coat.
If the ceiling is in real poor shape once primed you can spackel over the rough spots and sand to smooth out.

The brown your seeing is not mold, its the wallboard material under the paper. Many older drywall products had a brown core, not the white we are used to seeing now.

However if the brown spots are circles and are caused by leaks from the roof or room above, you do have a mold issue and need to remove the ceiling boards and replace them with new. I suggest that you use the Densarmor sheetrock sold at lowes. its a fiberglass faced wall board product that does not grow or support mold. It is also resitant to moisture as is the green board. Cost about the same.

One last thought. Be sure to wear a mask if the house is older. There is always the possiblilty of lead paint in this material.

As far as insulation above. Cooler attic temps or ceiling joists because of lack of insulation along the edge of the ceiling at floor level will cause moisture to condense due to cooler ceiling temps. Get some insulation in this space and install a bathroom exaust fan and the issue with the peeling paint should subside.

Thanks so much for your responses.

I'm painting my house to get it ready to sell, so ripping out the existing wall board is not an option. I'm doing this by myself w/out my dear dad around for consultation & 84 years of do-it-yourselfer expertise & willing labor. You work w/ what ya got, right?

The tile goes up to the shower head level, & it's just above there that the paint was peeling. The bathroom has a vaulted ceiling & the ceiling is fine. The green board was intact in most places, w/ just a bit of brown showing at the edges of the flaking area. I used sandpaper & then a putty knife to get rid of the peeling paint, then went over the whole band around the tile edge w/ Zinsser primer twice. Actually, I primed up to the ceiling in the shower stall to prevent this from happening to the next people.

The house is 20 years old, so there shouldn't be any lead issues. Unfortunately, the bathroom doesn't have an exhaust fan b/c it's got windows, which I don't open when I really want a hot steamy shower. In turn that also caused the edging tape to crinkle way up at the 14 foot level at the peak. Oy yoy yoy! Steam does amazing things.

If the peeling is starting next to the tile, be sure to clean the area well as soap has collected from splashing on the wall which will prevent the paint from properly sticking.

The hot steamy shower is why everything as you now know is peeling.