Yo seem to think that queries of this form are ambiguous, but they are not. Given the set of shirts, and that the subset of 'shirts with stripes' is well-defined (which you apparently accept, given that you seem to think that 'shirts with stripes' is an unambiguous query (which it is)), then its complement is well-defined; there is no 'Russell's Barber' paradox here, as there is no self-reference.