I know the effects on the curve. I'm challenging the notion reduced exposure can provide better separations. To me it seems like if anything it would have the opposite effect since it shifts more of the exposure values into the part of the curve where compression is taking place.
Regarding the sources of flare in testing etc, again, I'm refering mostly to flare caused by the subject/test target, not the lens. The kind of "veiling" lens flare Adams refers to is likely a relatively minor issue with most contemporary lenses.
Regarding the separation: My impression is that flare works very much like pre-flashing, the greatest effect is on the lowest values. The more you pre-flash the flatter the toe gets. Less pre-flash/flare exposure as a result of less total exposure means a steeper toe.
As to source, uhhh.
Mark Barendt, Beaverton, OR
"We do not see things the way they are. We see things the way we are." Ana´s Nin