How often should painted walls be washed?

Spot clean marks as they appear. Full wash annually. Kitchen walls and hallways may need more frequent cleaning.

What paint finish is easiest to clean?

Semi-gloss is the most washable, followed by satin. Flat and matte are the most difficult and most easily damaged.

Use a degreaser or dish soap solution. Apply to a sponge and gently wipe. Rinse with clean water.

Yes, but clean and prime first. Stain-blocking primer prevents stains from bleeding through the new paint.

Household

A clean painted walls makes a bigger difference than you'd think. Here's the most effective method, plus the mistakes most people make.

1
Dust the walls
Use a dry microfiber cloth to wipe the walls top to bottom, removing cobwebs and dust. Or use a Swiffer-type duster.
2
Test your cleaner
Test your cleaning solution in a hidden area. Different paint finishes (flat, eggshell, satin, semi-gloss) react differently.
3
Wash from bottom up
Dip a sponge in diluted Vibes Multi-Surface Cleaner, wring it well, and wipe walls from bottom to top in overlapping strokes.
4
Rinse and dry
Follow with a sponge dampened in clean rinse water. Dry each section with a microfiber cloth.

TIPSatin and semi-gloss finishes are the most washable. Flat and matte paints are delicate -- use the lightest touch.
TIPMagic erasers work wonders on scuff marks but can remove flat paint if you press too hard. Test first.
TIPPaint high-traffic areas (hallways, kid rooms) in satin or semi-gloss for easier future cleaning.

XScrubbing flat-finish paint aggressively, which creates shiny burnish marks visible in any lighting.
XUsing undiluted cleaners, which can strip or discolor paint.
XWashing walls top to bottom, which creates dirty drip streaks on clean sections below.

Yes for satin and semi-gloss. Use very lightly on flat/matte paint -- it acts like fine sandpaper and can remove paint.