The problems dust can cause to your guitar are not obvious at first, but build up over time. Each time you handle a guitar, dust on outside surfaces mixes with sweat, skin oils, dead skin cells, and other foreign substances to form an unattractive, abrasive film. Eventually this film will make the finish dull and cloudy and can damage the wood itself. Dust accumulates inside the guitar body of acoustic guitars, where it attracts and traps moisture, deadens the natural resonance of the wood, and degrades the sound. If your instrument is fitted with an internal pickup, dust can collect in and around the pickup, which can cause crackling, poor tone, or a weak signal. The pickups on the outside of an electric guitar are even more vulnerable. The magnetic fields attract dust, which is bad news for electrical connections. You may experience popping or crackling noises, a weak or inconsistent signal, or the signal may even cut out completely. Strings are also targets for dust. Each time you play, you grind dust into the windings. The result is a dead tone and reduced string life.
Keeping your guitar clean is common sense. A case provides the best storage protection, but if you prefer to leave your guitar on a stand, use a cover. While some players are content to use an old towel or sweatshirt to protect their guitar, these are unattractive and don’t shield the entire instrument. Look for a cover that provides full coverage, is easy to put on and take off, and is made of fabric. Avoid vinyl, as the plasticizers soften and discolor nitrocellulose lacquer finishes.