Today, it is mostly myth, built up by years of poor build quality from the 80's. It is pretty much a carry over from the dark ages of domestics.
I feel that american cars today are equal, if not superior to, in some cases, to their japanese counterparts. (Chrysler being the exception, of course!

)
I have a strong dislike for german cars, however, (not from a driving standpoint, but from a mechanic's point of view) so I tend to look down on some of them.