I have seen slight cases of this and extreme cases. Obviously, the slighter cases are the easiest. Salt is a mineral that easily dissolves in water but if it is dry, it can be brushed with a stiff brush then vacuumed up. Always try to remove in the dry state because when water is added it will become invisible. Too much moisture will result in a wicking problem.
Summary: 1) Brush & vacuum till your sick
2) Utilize a LMCC process.
3) Set fan to speed drying time.
In extreme cases, wet the rim of your glass, rub the rim on the carpet and fill w/ tequila.