I board early before the gate people go into "whatever" mode, crosseyed waving through whoever. I want them to scrutinize that BP so I end up in the right city.
My last flight, I'm walking down the steps to the tarmac and the boarding-helper-lady said "mwah bla bla wa wa wa?" (presumably "flight to Baltimore?") and I automatically said "yes" because I am so socially suggestible and all (I have got up and attended other people's medical appointments when the clerk has called a name and looked me in the eye. Once, the error was only noticed when the nurse remarked "I" had lost 30 lb in the past week. I now demand to look at the chart so see if it says MY name.) So I snapped out of my own automatic "whatever" mode and said "here - this boarding pass is correct. Does this airplane match this boarding pass?"
A Dash 8 is bad enough, but a Dash 8 to the wrong destination, priceless.