Yes it means shepherd but it also used as a derogatory term describing one who is unkempt and uncultured ie. roaming the wild country side with only his flocks for company. I am a Vlahos by birth (and proud of it!). However, there are parents of friends of Greek background who often do a double take when I tell them my name. It is very common in the Peleponnese and also the island that my father is from, Lefkada ( also known as Leucada, Lefkas, Santa Maura).