I don't know if it's because I spent most of my teenage years squinting at stuff due to my increasingly bad vision but I've always found them easy to see... just cross your eyes a bit and it materializes.
Magic Eye pictures remind me of that dancer image for some reason... I like to switch it back and forth like a light. I flick my eyes at the foot she's using as an axle and it's all subjective. Also, if you concentrate on that foot it can also look like she's just skipping from one side to the other like a scratched CD. Weird eye tricks are fun!