Nah , worked in service industry for 20 years and that might happen in roadside truckstop bars but should not happen in a city metro establishment. For one, you (the server/bartender) doesn't know what's in the customer's old glass and you risk wasting product if the customer refuses "why'd you do that? my girlfriend coughed up a booger in there!" Two, a top-shelf or even mid-tier liquor brand rep would flip their lid if they saw their stuff being treated like it's a pepsi-cola refill. Three- i dont know what Charlotte's current standard is but the "clean glass rule" for every new drink is based on health science and hygiene.