Do you ever wonde why your favorite pair of panties has runs and ladders in them and your others don't even though you wear them all equally the same?
EXCELLENT question, Puss!! Sometimes, you'll find, in your new clothes, a tiny paper tag that says: "Inspected by No. 17". Seventeen may have been overworked, towards the end of his/her shift, and, some stuff gets past them. Items that may have been handled just a little too roughly by the cutting and sewing techs. Or, the loom that knits out the bolts of Tricot, may have experienced a little hiccough, as it went through weaving the raw yarn. Oftentimes, the just-finished fabric goes through a chemical sizing bath, prior to further workage, and the formula may have been just a bit askew. Or, the drying temperature may have been a tad high.
All I know, further, is if the run/ladder/pilled/scuffed region is right in the "Winkie Zone", those panties are just about useless. Because if you try and mend them, even with the tiniest stitches that you can do, you're still going to get that annoying, irritating clumped little bump slapping Winkie's face.
Oftentimes it turns into more "error", than trial, when you're using trial and error to determine just how durable an unfamiliar Tricot is, if you're not careful.