Most of the time I can tell they are just reading off the tablet - and I am ok with that. Earlier this week the FA called me the wrong name...I said "no" and he mumbled something about "oh yeah - someone else was sitting there - I got ya, I got ya" but I noticed he never came back with my real name. I was the only F upgrade on the flight so there could have been something odd, but he was clearly uncomfortable with the situation. And during the thanks for flying with us greetings he was using names until he came to me and reverted to the generic greeting. It's not his fault but the technology clearly failed him...