This problem was discussed by Balona66, who used an analysis of the total bolometric flare energy to conclude that it is unlikely that the observation of superflares on A-type stars can be attributed to contamination. (nature.com)
Pecaut, M. J. & Mamajek, E. E. Intrinsic colors, temperatures, and bolometric corrections of pre-main-sequence stars. (nature.com)
MUSTANG - 2 sensitively maps broad - spectrum emission on the sky in the 70 to 105 GHz range using 210 individual bolometric detectors, each coupled to the sky with its own feed horn. (greenbankobservatory.org)