At SFO I caught a "security" officer in the act of stealing my carry-on. She walked away from the checkpoint with it as I was dealing with her colleagues. I saw her enter a door off to side of the concourse, dashed down there, opened the door. The woman who had walked off with the bag was spreading my stuff across a desk while another one pawed through it. I grabbed the bag and started stuffing my stuff back in it - they didn't even pretend to have any justification for walking off with my bag. If I could have found an actual cop, I would have tried to press charges.

I've also noticed the SFO staff can be very verbally abusive for no apparent reason, getting right into people's personal space and yelling into their faces, especially with non-white travelers.