The text has an obvious directional "flow". If you know that Chinese reads from left-to-right, the long tail under the third-character in the big yellow line and the ellipsis at the end of the text under the box are pretty strong cues. The separators in the line above the big yellow line are more plausibly slashes than backslashes.

I also want to say that I've seen a bunch of the glyphs enough time that they look wrong backward, but I might be fooling myself there. For instance, I think one year of Japanese classes is enough to say that the second character in the big line and the fourth character in the line below it look "wrong" mirror reversed; maybe that's enough that I don't count as totally illiterate.