I had a friend who used to be called in by other friends when they were interviewing prospective flat-sharers.

"John likes Wagner, don't you, John?" they'd say if they didn't like the look of the prospect, and John, wild-haired, wild-eyed and wild-bearded, would nod and grunt. "Uh-huh. LOUD Wagner's best."

Maybe you could import a "neighbour" - "This is my neighbour Merv. He's part of the local Wagner association."