I first noticed this when it was added as a sin for the X-Men (2000) video on the CinemaSins YouTube channel. When the guy voicing the sins states the following as Cyclops blasts the slime from Jean Grey's face:
"Cyclops has no idea what this substance is that Toad trapped on Jean's face, so how does he know what sensitivity level to set his visor in order to destroy the mysterious substance of unknown makeup but not injure her face?"
Can someone help me with this? Any sources from any comics, movies, scripts, or animated material is accepted.