Having an online presence is very important as an accompaniment to a CV. I always google job applicants that I receive. If I don't find anything, I am disappointed and tend to file those applicants with the ones where I find their fully open Facebook profile showing what that person did with a stripper at their mates stag party. LinkedIn provides a good fill for the void of wanting to fully lock down your Facebook profile.

Is it preferred for an applicant to conceal their enjoyment of parties, or for them not to enjoy parties at all?

Enjoyment of parties enough to make good conversation on Mondays, yet not so much that discretion is forgotten.