1. If you look at the first Officer, you will usually see that they've got an extra "trainee" name tag-type thing.

2. I watched a guy who had trouble getting his phone to scan properly asked for the phone by an Officer. The guy refused and the Officer told him he could either hand over the phone or go back to the counter to get a paper BP. TSA at DCA is pretty effective and quick. Guy handed over his phone, Officer got it to scan, handed it back, smiled and said, "thank you sir." Problem solved.