Answer:
The 12th century observer and writer Alexander Neckham recorded that in his time few men shaved regularly, meaning that even those who were "clean shaven" had obvious stubble. Many people preferred to grow a beard, since shaving was at best a difficult task. Neckham wrote that it was such a painful experience that it was generally done only once a week.
Long hair would first be cut with shears (there were no scissors until the late 13th/early 14th century). Then a small, sharp knife was used to scrape away the remaining hairs, possibly with the aid of lye soap or simply with hot water. Monks had their heads shaved in this way several times a year, meaning that on most occasions their heads were scruffy and stubbly.