Use the same color and finish (flat or semigloss), do a good job that leaves no visible edges, say nothing, and they’ll never know. ;o)

My son was awful on walls (bangs, scrapes, and “I didn’t do it!” stains), so I bought the cheapest latex paint I could find (most apartments are an easy-to-match off white), put down a newspapers (tape ‘em in place to form a solid surface that can’t slide and leave carpet exposed) or a drop cloth, blue-taped what should be masked off, removed outlet and switch covers, and painted. (And be sure to get a sitter while this is going on — small children WILL play in the paint.) No one ever noticed, and I never lost a nickel of my deposits.

Sometimes I could just paint the spot, other times I had to paint a whole wall. If your color matches closely, slight differences between walls will not show if you are careful in masking off corners.

Something bled through? Use KILZ primer to cover nastiness like Sharpie ink, let dry, then paint another topcoat over the KILZ.

Make a boo-boo? Have a wet rag (an old washcloth works best) ready to wipe up latex spots before they have a chance to dry. If you move quickly enough, you can even get fresh latex paint drips out of most carpet! Boo-boo dried or is really bad? Use Goof Off latex paint remover on a rag to remove the mistake.