I have, in the past, made kilts where the twill line ran the opposite of what is normal, because I was using cloth from a mill that was simply made with the twill line running that direction on the right (good) side of the fabric, as Barb has described.

To me, it was a fairly easy decision. Why is it customary for the twill weave in a kilt to run from the left knee up to the right hip? Because that's the way the twill will run if you make the kilt with the good face of the fabric on the outside, as it should be. No other reason, really.

So what do you do if you encounter a peice of fabric where the good face has the twill running the opposite direction? Well, in my opinion, you still make it with the good face on the outside.

Granted, much of the fabric from the better mills these days is good enough that you can hardly tell a difference between the good face and the reverse side; but that's not universally true. Sometimes you do get knots and thread ends and the like as Barb describes on the reverse side of the cloth.

To me, it's most important that the kilt be made with the good face on the outside, as intended. Even if that means that for this particular kilt the twill runs counter to what is "normal." How many of us pay attention to the direction the twill runs in our denim jeans? Why should it be that big of a deal in a kilt, really?