When I'm bored
I'll search twitter for what people are tweeting at United. It can be quite amusing. Plenty of passengers venting about delays, screenshots of text alerts from United about delays, many complaining about change fees, many tweet that "they'll never fly @united again," many "thanks for the upgrade" tweets with obligatory photo of feet in footwell, many complaints about boarding procedures (no family preboarding, not back-to-front), some asking to hold planes for tight connections, many complaints about missing checked bags.
If you can sift through that, every now and then you get some real doozies, from DYKWIA passengers or some pretty bad foul ups by United.