EDIT: I just went back and read my original post. I DO INDEED include the wording "...riding around looking for other people's brushpiles..." (which was used in the video) So I can see perhaps I caused some confusion there as to the context of my qustion. But my intent was not to question "riding around looking for other people's brushpiles" but rather, simply looking for brush, aka structure, to fish.
Somehow, trying to find some brush, stumps, logs or other structure at a creek mouth, on a drop-off, a point, off a dock, etc. doesn't hold the same context as "riding around looking for another man's brushpiles", but maybe that's splitting hairs. Lord knows, I don't want to do anything that would offend, cause confrontation or otherwise ruin someone's day fishing, they're too precious and life's too short.
I don't think anyone would question the poor ethics of, rather than prospecting and finding productive spots, following another around as they sink brush, or fish certain spots, and targeting their spots based on what could only be defined as "spying".