A citation for the common complaint of butch lesbians being mistaken for men by strangers? I'm aware of no such study.
So you don't know how common it is.
And you are confident that:
There is more than enough variation among the sexes to make trying to identify sexual dimorphism at a glance a very risky proposition.
Except this is not what studies show eg
https://journals.sagepub.com/doi/10.1068/p220131People are remarkably accurate (approaching ceiling) at deciding whether faces are male or female, even when cues from hairstyle, makeup, and facial hair are minimised.