The really, really super-white teeth. Seriously: Just to keep from blinding us with Georgia's superior dental hygiene, the record company really should have Photoshopped those choppers gray.
As for other characteristics that might make it easy to tell him apart from fellow rural hunks like Jake Owen, Chris Young and Eric Church, that's a little tougher.
"Tailgates & Tanlines," Bryan's pleasantly sung and modestly accompanied third album, isn't half-bad, but it goes out of its way to remind you of a hundred country songs you've already heard in the past few years.
And that doesn't leave nearly enough individuality to sink your incisors into.
Too many of the songs fall victim to the modern country trap of simply listing the trappings that make rural Southern life great, even when the theme is romance. The title is not accidental: Girls dancing on tailgates show up in both the first and third tracks, and that's even before you get to the song that has a tailgate in its title.
At least in the album's first half, emotions end up taking a back seat to the familiar tropes of tractors, four-wheel drives, and moonshine.
This is true, surprisingly, even of the lead-off single, "Country Girl Shake It for Me," ostensibly a barroom rump-shaker in the tradition of Trace Adkins' "Honky Tonk Badonkadonk" and Big & Rich's "Save a Horse (Ride a Cowboy)." Bryan is describing a sexy dancer's down-and-dirty charms, but by the time he tells her to "shake it for the catfish swimming down deep in the creek, for the crickets and the critters and the squirrels," you wonder whether he's really set on a booty call or becoming a Junior Ranger.
In at least one case, rural specifics work in Bryan's favor, because he's not using them as a backdrop to liven up an otherwise generic love song. "Harvest Time" is the rare country song that actually celebrates a farming community, as opposed to the contemporary overuse of John Deeres as some kind of country aphrodisiac.
A few sadder songs later in the proceedings turn out to be standouts, if not necessarily obvious choices for follow-up singles.
The ballad "You Don't Know Jack" tells a tale of alcoholic woe that half-cleverly plays off the titular whiskey pun. "Tailgate Blues" takes the dancing girl off the back of Bryan's pickup and puts the lonesome singer there instead, out in the wilderness, crooning, "I catch my buzz in the black of night." And the album finally slips into the sheer poetry of lost intimacy with a closer co-written by the great Radney Foster, "I Knew You That Way."
There, the bygone love Bryan is lamenting is so strong, it doesn't even make him think about catfish.