This is the bridge pickup cavity of my Ibanez S1XXV. The white gunk there- dust. The fact that it didn't get mixed into the finish means that it was there after the paint was applied. Highly likely, it's the bits from holes drilled into the cavity. The inspection label, all initialed, implied that the situation was acknowledge before the cavity was covered (by the pickup). To give the benefit of the doubt to the people whose initials are clearly seen here, they might be inspecting the instrument for something else & dust busting isn't part of the job scope.
It's a shame that Ibanez (Indonesia) didn't put in that little extra bit of consideration in ensuring the cavity was cleared. I simply had to brush the dust off, nothing to it, really. I can imagine the factory, being equipped with tools, machines & implements to attend to this simple feat but it wasn't done. Job attitude contributes to the goodwill of the company, remember that, my friends.