I don't know how other people experience it, but it's not like a full-blown hallucination as the exercise would imply. Personally I experience it as something in between the concept of an object and the perception of an instance of one.

If someone says they're looking for a purse I would still have some ambiguity, visually represented, about the material, color, texture, shape and size, type of clasp, if it has a strap or a chain attached to it, if it was new or showed wear, if it appeared to be ful or empty and flat...