United Economy Plus

I tried to get our seat assignments the day before we flew (Sunday night) but couldn't because even though there were empty seats; they were unassignable, for some reason. So, we had to check in the morning of flying (Monday). When we did, the woman checking us in asked if we wanted to fly Economy Plus, with "up to 5 inches" extra legroom for $50 per seat. I said no (because of that sneaky "up to").

When we sat down, I noticed that the tray table in front of me had an Economy Plus sticker on it. We were in Economy Plus anyway! That's why the seats were unassignable as regular seats the night before! So, that appears to be United's new strategy:
1 - make a handful (about 12) seats Economy Plus, with a tiny bit of extra legroom
2 - overbook the rest of the regular seats
3 - fill all the regular seats with online check-ins, offering Economy Plus
4 - offer the Economy Plus to everyone who checks in at the airport
5 - fill the extra Economy Plus with the overbooked passengers anyway

I heard other people in the check-in line pay the extra $50. I'm glad we didn't. Good to know for the future: They sold me a seat, they have to give me a seat. If I check-in the day of, that'll probably mean a free Economy Plus seat.