In film days, it was very common to check for "hair in the gate." Now, I want to verify that I have no dust specks on the sensor. No matter how careful you are when changing lenses, stuff happens.
Do you think that a useful tool for this might be a Retina MacBook Pro? Both because it has such high resolution, and because it is a computer, with Photoshop's Magic Wand tool which is so good at finding sensor dust.
Adobe used to have software which enabled you to use a laptop as a field monitor and maybe even grab a still frame. Does this exist in any form today? (I know I can always simply capture footage as if I'm beginning to edit, but the goal is to avoid any interruption in the flow of the shoot.)