Nice idea, it might find some quirk of the face detector though, and exploit that, instead of producing a truly face-like image.
On the other hand, I vaguely recall a talk by VS Ramachandran where he claimed that in essence that's what Picasso and many others did also, i.e., you might see a painting that objectively doesn't strongly resemble a face, but it hits the right spots in your brain's face detector, so your brain says to itself "now that's what I call a face". A bit like how colorful candy triggers "ripe fruit - eat it!".
For the standard Haar-based Viola-Jones detector, all the parameters needed for it to say "yes" to a detection are known ahead of time if the detector is already trained.
They consist of adding and subtracting different rectangles within the image and comparing the sum to a pre-defined threshold (this is called a "weak classifier" in this context). This is done for ~30-50 different weak classifiers and if all of them pass, then a face is declared there.
Therefore, it should be relatively easy to find a set of rectangles that would satisfy these conditions.
My guess, from having worked with face detectors for quite a while, is that it wouldn't be nearly as cool as what painters do -- the false detections would be more mundanely like faces, or so completely off-the-wall if they happen to be a pathological case.
"In this series of images, all pulled from a single stone, Picasso visually dissects the image of a bull to discover its essential presence through a progressive analysis of its form."
On the other hand, I vaguely recall a talk by VS Ramachandran where he claimed that in essence that's what Picasso and many others did also, i.e., you might see a painting that objectively doesn't strongly resemble a face, but it hits the right spots in your brain's face detector, so your brain says to itself "now that's what I call a face". A bit like how colorful candy triggers "ripe fruit - eat it!".