Word(s) to describe the emotion behind disappointedly looking over ones glasses?

Solution 1:

to give someone a quizzical look.

expressive of puzzlement, curiosity or disbelief

quizzical

Examples: But in general, as befits a covert operative, his tone is quizzical and low-key, rather than bombastic and judgmental. For anyone schooled in blackboard economics, "The Undercover Economist" succeeds in taking the chalk dust out of the subject. The Economist

It makes up for the quizzical glances that leap my way when I stow away on scriptwriting courses or lectures on psychology. The Guardian

Ludwid guru is a great tool! See the two examples above.

Solution 2:

Perhaps "askance" would aptly portray it as a "look of incredible disbelief" (Are you serious...?).

TFD - askance