Before our cruise, I looked up private tours in Bar Harbor and found At Your Service Taxi, and they sounded exactly what we were looking for. So when our cruise ship arrived at Bar Harbor, we got into a minivan that we thought was At Your Service. To make a long story short, the minivan stunk like smoke, the driver smoked a cigarette at every stop (and smelled awful when he got back in), and didn't know squat about the history of the island. I studied a little before our cruise, and I knew things he didn't! He even mentioned some story about someone on the island, totally irrelevant. Well, guess what. When we had asked if he was At Your Service at the pier he said yes, but this wasn't even At Your Service taxi, it was Coastal Cab company who shows up at cruise ships and tries to look like At Your Service because it has such a good reputation on cruise websites.
At dinner that night, a couple was telling us about their tour, with the real At Your Service company. I'm really bummed because they got the tour I wanted and had looked so forward to. (Their driver was a retired school teacher who has lived her entire life on the island. They loved her.) Make sure your driver is wearing a shirt that says At Your Service, I wish I had.