I bought a pair (Bosch) that squeaked for two years before replacing them again (also Bosch). The second pair did not squeak at all. And my W124 windshield is FAR from blemish-free!
Perhaps the wiper inventory in some stores is a bit more aged than others?
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car