“cops are trained to look for suspicious activity”
Yeah, I am sure the legions of cops who only have a G.E.D.’s or HS Diplomas are secretly experts at thought detection. Everything you write is moot, BECAUSE IT WAS PRIVATE PROPERTY WITHOUT A WARRANT.
That doesn't make a difference. Police powers to detain someone extend to private property and do not require a warrant. If a cop sees someone breaking into a house on private property, or observes someone removing drugs from a car on private property, they can go in and arrest them on the spot.
Or do you think that once you make it onto private property, you're immune to the law?