Painting over reversed drywall
Three coats of paint here is insufficient, or rather inappropriate. This surface needed a good sanding, and probably some ready-made drywall joint compound, to make it even and clean. 

Then one coat of primer and two coats of paint (until nice). In the current condition, I'd be afraid whatever you put over will flake sooner than later due to the bad base.

Personnaly, I'd have gone


drywall compound till nice all around
sand evenly
primer
2 coats.


I assume all those racks and shelves were removed prior to painting, right ?

From the current condition, I'm not sure how much sanding would give enough for the new paint to hold.