only in the mirror universe!
Revision: Both Spock and Sybok have been shown capable of growing facial hair. However, facial hair does not seem to be the norm or in-style for Vulcans. The problem is that both instances involved Vulcans who were not affiliated with what can be considered the normal Vulcans.
Also, in the episode "Year of Hell Part I," Tuvok is seen shaving (while blind).