Your jeans tale reminds me of an issue I have that I find completely inexplicable. I have two identical pairs of shorts that I bought from Mountain Warehouse at the same time several years ago. They're the only pants* I wear routinely, in rotation every washing interval. One pair is completely fine, but the zip on the other pair simply will not stay up. I've been caught out once in polite company and twice in public in the last week. As they refuse to wear out they have now been relegated to gardening use only (we have no neighbours).

*Pandering there to American usage of the word. I do not refer to my underwear on Mudcat...

:-)