Two-Tone-Blue
Misunderstood you, sorry.
Not saying everyone finds IAD to be an unpopular destination - it's probably one of the least liked cities in the US - but when it's part of a B2B most crew don't mind because of the money - money talks. Commuters also love B2B because of the hotel they get at LHR because they don't need to book other hotel or B&B.
So, yes - you as a passenger are paying for it and I'm sorry you find the crew most of the time to be grumpy!