The short answer is "it depends".

The longer answer is basically drawn from Robert Parker's landmark Miasma (on "pollution" in Greek society), specifically the chapter "The Works of Aphrodite". He brings up your Plutarch example as an "exception to the rule" - but also note that Plutarch states the priest cannot have sex with a woman, but men aren't off the table.

Being a priest or priestess in itself did not demand any kind of vow of chastity; it was a part-time position often thrust upon people by lot (if we're talking "5th century Athens" for Ancient Greece, at any rate). Most of the year you wouldn't have to be doing anything particularly different from your normal life, and the importance of (male) heirs to continue the family bloodline was such that abstention from sex wouldn't be practical.

Sex did make you "impure", yes - but this impurity could be removed either by simply waiting until morning, or washing at the boundary before entering a sanctuary, so it wasn't something that was a major stumbling block on the way to holding religious office.

With that said, according to Parker, the stereotypical view of most priests/priestesses in important positions was that they were "done with sex" - men and women over the age of 60, perhaps.

With regards to "different strokes for different folks", it's a little difficult to separate fact from fiction. The most famous example of a religious devotee abstaining from sex that I can think of is Hippolytus in Euripides's tragedy of the same name, but that is depicted as being both impious and destructive (he dishonours Aphrodite by devoting himself to Artemis and the hunt - and as a male devotee to a goddess is already transgressing social norms). Virgin priestesses for virgin goddesses seemed to be in existence, again according to Parker - but these would be very specific cases.