Assuming that type(expr, polynom) is true, then type(expr, expanded) will return true if expr is an expanded polynomial, false otherwise.

$\mathrm{type}\left(\left(4xy-x\right)\left(x+y\right)\,\mathrm{expanded}\right)$

$\mathrm{false}$

$\mathrm{type}\left(4x^{2}y+4x{y}^2-x^2-xy\,\mathrm{expanded}\right)$

$\mathrm{true}$