As an expert sommelier and brewer, I can assure you that there are several ways to determine if a glass is clean. While the water test you mentioned can be a good indicator, there are other factors to consider as well.
1. Visual Inspection: The first step is to visually inspect the glass. Hold it up to a light source and examine the interior surface for any visible residue, such as fingerprints, lipstick, or soap scum. A clean glass should have a clear and transparent surface without any obstructions.
2. Water Coating Test: Your suggestion of dipping the glass in water is a simple and effective test. Fill the glass with water and observe how it coats the inside. A clean glass will show an even and uniform coating of water without any droplets forming. If you notice droplets or patches where the water doesn't stick, it could indicate residue or oily film on the glass.
3. Smell Test: Another way to assess the cleanliness of a glass is by giving it a sniff. Clean glasses should have no odor or any unpleasant smells. If you detect any off-putting aromas, it could be a sign of residue or improper cleaning.
4. Touch Test: Run your fingers along the inside of the glass. A clean glass should feel smooth and free of any sticky or greasy residue. If you feel any tackiness or roughness, it might indicate that the glass needs further cleaning.
5. Beer Head Retention: When pouring a beer into a glass, the cleanliness of the glass can affect the quality of the beer. A properly cleaned glass will promote good head retention, with the foam forming a consistent layer that lasts. If the foam quickly dissipates or appears patchy, it could be due to residual oils or dirt on the glass surface.
6. Taste Test: While this may not be a foolproof method, some people claim they can detect a difference in taste between beer served in a clean glass versus one that is not. Residual soap or other contaminants can potentially impact the flavor of the beer, so if you notice any off-flavors, it might be worth reevaluating the cleanliness of your glassware.
It is worth mentioning that using a dishwasher or hand-washing technique with hot water and mild detergent is generally sufficient for keeping glassware clean. However, certain factors like hard water or improper rinsing can lead to mineral deposits or soap residue on the glass. Regular inspection and cleaning will help ensure your glasses are in pristine condition.
In my personal experience, I have encountered instances where glasses appeared visually clean but still had residue or oily films that affected the aroma and taste of the beverages. Therefore, it is essential to rely on multiple methods of assessment to ensure the cleanliness of your glassware.
Remember, clean glassware enhances the drinking experience by allowing the aromas and flavors of your favorite beverages to shine through. Taking the time to ensure your glasses are clean will undoubtedly enhance your enjoyment of various beverages, whether it's beer, wine, or spirits.