You would be surprised what is sold through all major retailers.
I used to work in warehouse where we handled lots of ladies lines of clothing.. outer and under garments.
Majority of 'stuff' was made abroad so our job was unpack it all and made them exeptable condition for shops. Most of the time it was just matter of steaming and ironing but every now and then there was some surprises... whole shipments having to be fumigated because of all manner of insect...oil stains (having to spot treat them)...food stains and smell (mostly curry whiffs), so it was either washing the whole lot and/or spraying tons of Fabrese over thousands pieces of clothing
Those were just few examples what was going on behind the scenes then...and I don't believe it would be any better now.
I NEVER EVER wear anything from shops, part coats, jackets and shoes without washing them first.
At the moment lot of the clothes are very poor quality where ever you go...just cheap materials used to make maximum profit.