The dead give away is of course the facial hair. What does Singing Spock look like? (How many albums did he make?) And, what is the difference between Trekkie and Trekker? Saw the documentary, but I cannot remember.

you can find Mr. Nimoy's complete discography here.

He's most famous for his rendition of the Ballad of Bilbo Baggins.

We all know the Shat's propensity for releasing albums, and given this, it must be a contractual requirement that Trek cast members record music, because in addition to Nimoy and Shat, Brent Spiner (Cdr Data on TNG) has also released an album or two, most notably Ol' Yellow Eyes Is Back.