Interior paint typically gets dirty in many situations: hand prints around switches and knobs; splashes in kitchens and bathrooms; marks on hallways and corridor; “soot” accumulating above electric lamps and other heat sources. Removing dirt before it accumulates not only improves appearance; it reduces chances of it getting permanently embedded in the paint film.
Check for dirt periodically; and assume it will be present in and near cooking areas (airborne cooking oil) and at all places at hand height. Always initially clean the surface with a mild detergent with a sponge or a soft cloth; resort to harsher cleaners only when necessary, recognizing that alkaline cleaners can dull the sheen or gloss of oil based paint. Abrasive cleaner will burnish nearly any paint, and will dull the gloss of satin, semi gloss and gloss products. Washed surfaces should be rinsed thoroughly because residual cleaner can interfere with adhesion of paint applied later.