I have just found this:
The Gratuitous Umlaut
An umlaut is a diacritical mark consisting of two dots placed over a letter to alter pronunciation. However, the so-called "heavy metal umlaut" is used in the names of bands, such as Mötley Crüe and Motörhead, not to change pronunciation, but to evoke the stereotypes of boldness and strength commonly attributed to peoples whose languages incorporate such marks
. It has since been widely parodied, including in the mockumentary This Is Spin¨al Tap. Which band first used a gratuitous umlaut?
Acording to this, there are stereotypes of boldness and strenght attributed to people whose languages has "umlauts" (letters with two dots).
That would be the Germans, the Austrians, the German speaking Swiss and the Turks. And the Hungarians.
Never heard of such a thing, but I think I like it. He, we are bold and strong! And others, Englishmen maybe, are cowardly and weak!