When the beard made its first appearance in "Through the Looking Glass", it didn't look too hot. Neither on Jack nor as far as looking realistic as a prop. The mustache hung down as if it was its own entity, while the rest of beard looked a bit light in color compared to Matthew Fox's natural hair color. But more importantly, this was JACK. How could Jack, who favored buzzcuts and a light scruff, go for a full-on beard? Hurley, once again working it as the audience's mouthpiece, said it best when suddenly confronted with the image of a bearded, way-scruffy Jack:
JACK: Thinking about growing a beard.
HURLEY: You'd look weird with a beard, dude.
You should've listened to Hurley, Jack. In any case, Jack defied all reason, and grew the damn thing, that even Kate was pretty much repulsed when she saw him after their big break-up in "Something Nice Back Home". All the make-up she had plastered on couldn't hide her shock at seeing him since she'd last found him wallowing in beer and paranoia, just after their happy engagement.