I've purchased MANY parts from "MU" in 15 plus years - they WERE a good source until about 8-10 years ago when they expanded and started chasing big money - IE CHEAP CHINA crap.
While I am still a customer of "MU" I VERY carefully examine every part I buy from them. I have the good fortune that my office is only 2 miles from their Atlanta warehouse.
I've had similar "bad" reactions to parts from Cali Mustang, NPD, AutoKrafters, and several others - even when you ask they do not always know where it is made or of what "quality" it is. I've even gotten "BAD" NOS FoMoCo parts - so it isn;t just the repo stuff.
Sad to say it is a reality of our hobby and the economy - plus the Muscle Car Craz.
I have been very happy with almost all Scott Drake parts - he seems to really care about his part quality. So I ask for his parts whenever possible.