Short version: they looked a lot more like 
than 
. Most accounts of Vikings that are contemporary of the centuries where shield-Danes and spear-Danes went "a-Viking" describe distinctly hygenic people that bathed and took care of their hair (and wore it long).
EDIT: I thought I could have a little fun with a very loosely associated Beowulf reference to Danes (and even more loose associations with Geats therein too) but I got the 
experience for doing so. 
They didn't have Hitler Youth fades with lazy and sloppy beard fusions. Period. Full stop. Stop doing that. Looking right the fuck at you too, P R E S T I G E T V. 
That was also the Rest of Europe's interaction with Europe. The Saxons were guilty of most of the same practices as the Vikings (and, indeed, had done the same thing as the Great Heathen Army 300 years before). The Franks were real pieces of work, the Carolingian Empire committing war crimes on a scale the Norse could barely imagine, and then blaming them for their decline and not the massive Civil Wars. And then we have the Gothic Wars, which did more to usher in Late Antiquity than Attila could have dreamed.
More evidence that the Moors shouldn't have stopped at Tours.
Dont forget the "holy" catholic crusaders who massacred non christians and also byzantines too!