Someone has found a way to see through, at least, some types of frosted glass. The feat is accomplished by placing clear tape on the glass. Youtubers have said that the adhesive on the tape smooths over the glass's roughness thereby making it clear. This would make sense if the optical properties of the adhesive is closer to that of glass than to air. If you are using frosted glass, be sure to place the frosted side facing the side that is to be kept private.
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