This is a normal before-after photo from an old bathroom photo from an old unit.
We painted the whole internal surface in this case too, but We wanted to show what is the different. we always clean and sand the old painted surface, scratch out cracks and seal bare areas. Fill holes and imperfections and caulk cracks (we used high quality, flexible gapfillers to fill up the gaps). Sand and seal filler.. Apply one coat of oil based undercoat and two coats of semigloss enamel on windows, doors, skirtings.