Some times I have run across an advertisement that implied a product was Made in USA but the product did not have the Made in USA label.  Before I buy or put the product on my Made in USA list, I email the manufacturer and ask if their product is Made in USA.  If they say yes I ask why their product is not labeled that way.  Seldom will they tell me why but many times they will tell me every component that is Made in the USA and those that are not.  I then make my decision about buying their product and put it on my list if they convince me.