[doctoboggan]

I am assuming you are joking but I see other people responding as if you aren't.

This isn't true as the spinning dancer illusion only works on silhouettes and not full color images.

[oceanplexian]

I squinted at the sandwiches trying to reverse their direction like an idiot. Guessing I’m not the only one.

[JKCalhoun]

The dancer illusion is as though you are observing the dancer from a long distance away through a telescope of some sort where things like her hands do not appear to vary in relative size as she turns and they become nearer/farther from us.

[StrictDabbler]

It also works on translucent objects and in a different form on the mask illusion, where a rotation depends on whether you believe the mask is bent away from or toward you.

Basically anytime that depth information is obscured.