There are several roads in the area where people typically drive in the left lane & pass in the right lane. Most of the people are smart enough to understand why & don't begrudge them for having to pass on the right instead of the left (the left lane is in great condition, the right lane is full of poorly filled potholes that stick up above the road surface a little bit, else are just a little below the road surface.)
Otherwise, I rarely encounter people who don't drive in the right lane when they're driving slower. Must be we have better drivers in this area. However, when traffic is moderately congested, i.e. typical traffic on the NYS thruway, I never cease to be amazed at the number of asshats who live and die by this "keep right" think. All the traffic in the right lane is going 65. All the traffic in the left lane is going 75. If you move from the left lane into the right lane, you're going to be locked into the right lane for the next 5 miles as a line of traffic slowly passes you at 75 mph. However, there will always be a dozen asshats in that line who think they own the road and that everyone not going 90 should get the hell out of their way. So, to those guys, "fuck you."
Now, since I rarely see people camped in the wrong lane, I have to wonder if some of the people complaining about people in the left lane are the asshats who simply believe that they're above everyone else on the road simply because they want to drive faster than traffic is going to allow.