Understand why people store their glasses upside down and why not to determine how you will do it.
Dust Prevention
Storing drinking glasses upside down prevents dust from settling inside the glasses, which is especially important if you have glasses that you don’t use very often that would have time between uses for dust to build up inside them. If you don’t store your glasses upside down, rinse them before every use to remove dust particles. If the dust layer is thick, run the glasses through the dishwasher before using them.
Pest Protection
If you have bugs in your home, you may want to store your glasses upside-down to prevent bugs from climbing into them, which will not only trap the bugs and kill them, but it will contaminate your clean glasses.
Rim Contamination Issue
One concern with placing drinking glasses upside-down is that the rim will become contaminated by the shelf, which is not a problem if you clean and dust your shelf often, but it is a concern for some.
Moisture Issues
Storing your glasses upside-down could be an issue if you don’t dry them completely. If there is even a speck of moisture inside the glass, it will evaporate in the glass and condense on the inside of the glass, which can encourage bacteria and mold to grow and will contaminate your drinking glasses.
Stability Concern
Some drinking glasses have a very delicate rim that was not meant to bear the entire weight of the glass. If this is the case, do not store the glasses upside-down, which will put undue pressure on the rim and could eventually break the drinking glasses.