The weak wine

Jack had enjoyed his time in Michigan but he was relieved to get back to his home in the nice albeit cloudy England. As he set up his agency again, he found a customer. 

Mr. Fordyce, the owner of the nearest supermarket was waiting. 

“Thank goodness you’re here!” he declared.

Jack went immediately to business.

Mr. Fordyce told him the problem.

While Jack was away, Ernie had set up a wine business which they claimed was backed by a premium wine connoisseur. 

“The business has been successful,” admitted Mr. Fordyce. “Everyone thinks the wine connoisseur’s wine will be tasty, so they buy it. I’ve tasted it. It’s terrible. But it’s making me go out of the wine business.”

Jack told him he’d look into it and he made his way to Ernie’s den. 

When he arrived there Ernie looked at him as he sat down and scowled.

“I would punch you in the face but I’ve spent the last hour crawling into icy cellars.” remarked Ernie. 

Jack’s heart raced. 

“Icy cellars?”

“Yeah. Icy cellars from our wine business. That connoisseur got us these new cellars. They’re cold.”

Jack sat down and a man walked out of the inner reaches of the den. 

“Hello, Ernie” he said briskly, then seeing Jack and stiffening. 

He was Billy MacBilly.

“So you’re that wine connoisseur?” Jack rose from his chair.

“Yes. I’ve taken multiple courses in wine-tasting. I’m a certified master.” said MacBilly stiffly.

“Drop this charade. Your mistakes are obvious.”

Why?