[seth00]

The 10 queens situation is obviously impossible, but so is having 2 white queens and black has all of his pawns on the starting squares.

It's more difficult than you're thinking. If white has 6 dark squared bishops, they you know that he promoted at least 5 pawns on dark squares so one pawn must have taken a piece since it's promoting on a dark square instead of a white one. Not every board set-up will have enough missing pieces that 5 pawns can maneuver to get promoted on dark squares.