[weird-eye-issue]

BuiltWith has gotten quite good. I tested it on my site and it even correctly detected I use Shutterstock for stock images. We don't credit Shutterstock anywhere (already pay them like $300/mo) so it must actually analyze the images themselves to make this determination

[mmahemoff]

Filenames maybe

[weird-eye-issue]

Nope my VA is trained to change all filenames to something description such as "dog-playing-with-leash.jpg"

[ayewo]

Or perhaps it uses file hashes to determine if certain images are similar.