Some of them are just horribly confused. In those cases, ask for a seat as far forward as possible.

A few months ago, I went standby on an earlier-than-scheduled LAX-ORD 2-class 777. I arrived at the gate as boarding was finishing, and asked for an E+ seat. The GA (politely) informed me that "2-class 777s don't have E+" (They all do). I tried to correct her once, but she didn't budge even as her coworker at the next station proceeded to hand out E+ seats! But by asking for the most-forward aisle seat she had, I got an E+ seat. Funny thing is, she somehow managed to print me a gold BP for that seat which did NOT say E+. The whole thing was rather weird.