I prefer to have my fabric ripped when I purchase it because it is on grain. If it looks angular when I hold the selvedges together, I know I have to 'tenter' it by pulling diagonally on the corners until it hangs straight. Having fabric on the straight grain is very important on sashings and borders. Perhaps it doesn't make too much on cut squares and triangles for quilt pieces. I know this harkens back to garment sewing when sections not cut on the grain did not hang straight. I am aware that this can cause a problem when the fabric has been printed on greige goods that are not straight to start with. I never buy printed plaid fabric for this reason. Sometimes we have to choose between two equally poor options.