IAD is very bad. I think these are all of them. Many start "your attention please" as if you have to drop what you are doing and just listen.

1. do not accept rides from people who approach
you in the terminal

2. do not accept items from unknown persons

3. report suspicious activity

4. smoking in designated areas only

5. for security reasons, do not leave unattended baggage

6. all bags are subject to inspection

7. "Will Jane Doe please report to Gate 14 for immediate boarding" -- these messages happen quite often now due to bag matching rules I imagine.