4406 even factory rotors we had some with problems.As for store brand like Advance etc we had little to none.Yeah every now and then a bad one but very very few.Did thousands in my timeas a tech.Oh yeah you wont beievethe total junk people want to have turned.had a Porsche that had rotors .250 under discard.thats not a misprint .250 and the guy wanted them turned.Let alone some with rust holes 1/8 to 1/4 inch deep or more.Rocky