[6ren]

Are there other examples of it working? (if there were links, I couldn't see them).

There's a danger of overfitting, where a technique works for one instance (or a subset of instances), but not in general. Detecting stripes could work in general, but as a SO commenter noted, "Where's Wally" images often include spurious stripes to undermine this detection strategy for humans.

[qntm]

To say nothing of that one Where's Wally image consisting entirely of imperfect Wally impersonators, with one real Wally identifiable only because has the correct hat, glasses and chin.

http://ecx.images-amazon.com/images/I/61eiboxUJhL.jpg