A video designed for bartenders has gone viral: it reveals how to tell if your glass is actually clean or just looks like it's clean.
The secret to telling whether or not detergent, oil, grease, or other residue is still taking up residence in your glass is fairly simple. The answer is: salt.
If the salt coats the inside of the glass evenly all over, your glass is 'beer clean'. If not, there are still oily or greasy deposits which will attract more salt.
'Beer clean' means that the glass is free of anything that could mess around with the taste of your beer, which people have meticulously brewed, transported, and stored to make sure the delicious flavor was still intact.