The worst I think for me (and I genuinely can't remember which seafront bar it was or I would name and shame) was sitting inside watching a barman making a very complicated cocktail for a few people who were outside. Not being where we were they were very lucky that they didn't see the barman who was adding each spirit by covering the end of the bottle with his thumb.
After each dash, he licked his thumb and moved on to the next bottle.