I try to watch both when my bag goes into the scanner and be waiting on the other side when it comes out. I’ve had more trouble with TSA than other pax:
1. I have been in situations where the TSA “officer” tried to steal items from my carry on when they were out of my sight, such as “removed for inspection”
2. The TSA clerk was working in cahoots with a fake passenger who tried to steal my laptop computer bag while the TSA clerk tried to get me to move out of sight of my bag to check me for an alleged security alarm.