One way to touch up your windows without water is by using 0000 grade steel wool. It will remove stubborn spots with just a little effort. It works especially well on fingerprints left by little ones. Also works for removing nose prints from pets. Make sure to use the oooo grade of steel wool so as not to scratch the glass. DO NOT USE on windows that have tinting film applied to them. It will scratch the tint. This type of steel wool can be found at Lowes, Home Depot and Wal-Mart.