use of mirror to test for sneaker males?

[illumnae]

would it work if i were to place a mirror into the tank and get the female in front of it to see if it flares? if she flares all the time at the mirror and (for some species) displays the flaring colouration, wouldn't it indicate a sneaker male?

[joopsg]

some female will be aggressive when not in brooding dress. Sneaker males sometime quite easy to spot because they still have loopshole indictating they are male. Like colouration on the facial.