Empty the ashtrays, wipe up drips, clean the dirty glasses. Your patrons should be able to lean their elbows on the bar without fear of wet spots. And if you see a patron cleaning off a spot at the bar, you're simply not doing your job. Having to wait too long for beer. This is a sin for bartenders, especially when it comes to your regular patrons.
People sit at the bar for a reason, and that reason is to drink, and to drink in a timely manner.
They should not have to use a flare gun to get your attention, and if you can't scan the bar while you're talking to your latest squeeze, then you're in the wrong business. If you'd like to see the Platonic Ideal of this, try the Ole memorial Lounge in Tulsa, where beers appear if you've got money on the bar and less than half a drink left. That may sound extreme, but a bartender like this makes good money, and packs them in. Bartending is an honorable profession, and should be looked upon as such. A good bartender is intelligent, has personality, and can converse with a wide range of patrons.