Ways to tell:
Skin color
Lauguage spoken
Color of flag they fly
Language of signs they carry
LOL! So, if I run across a brown-skinned person who speaks Spanish, has a Mexican flag anywhere, and listens to Hispanic radio, they are trying to overthrow our country??
Are you serious?
No...what I mean is if:
They are in a mob numbering in the hundreds..
Shouting "Viva la Raza"...
Waving Mexican flags...
Burning American flags...
THEN I would hope it'd be obvious.
If the National Guard couldn't distinguish between their own countrymen and the enemy of all they stand for, then we're blued, screwed, and tattooed.