Well my 2 cents worth about TSA at IAD:

The last 2 years i have been in and out from IAD airport about twice a month or even more.I have never faced agressive behavior nor bad treatment.
Once flying with my family we all got SSSS it was a nice and fast search even went through that puff puff machine our hand luggage was searched all in all it did not take longer than 5 minutes.

As i always carry my CPAP with me, the TSA always has it swipped but that also does not take long. Every time this is done i was asked very politly if they can open the bag. I really find that TSA at IAD are efficient and polite.

And i forgot to mention that i am a Saudi and a Muslim.

On the other hand i found TSA in Paris to be rude. In FRA i found them not smiling nor friendly but efficient.