Those Wacky Wine Customers!

I'm not complaining. I appreciate anyone who walks through our door here at The Market. You never know where your next great customer will come from.
But. Some interactions are just ... well ... funny.
A guy comes in the other day and interrupts me helping another customer to ask "do you have any dessert wine"? I say "I'll be right with you". And then the exchange goes something like this:
Me: I have a couple of great Sauternes here. This is a classic dessert wine.
He: Are they sweet?
Me: Yes. But they are balanced.
He: Anything not so sweet?
Me: These Muscats are more like port, but sweeter. Not as sweet as Sauternes, though.
He: Do you have anything white that's sweet but not as sweet as Sauternes?
Me: German Rieslings fit that bill nicely. (I proceed to show him several options at various price levels)
He: Do you have any I can taste?
Me: (Beginning to think this is going nowhere) No. Sorry, I don't have any Rieslings open right now.
He: Do you have any Moscato? (a slightly sweet sparkling wine, usually from Italy)
Me: Sure. (I show him several selections)
He: Do you have any I can taste?
Me: No. Sorry, we don't keep sparkling wines open because they "lose their sparkle" quickly.
He just kind of looks at me like I'm evil and proceeds to look at accessories.
He did actually buy one of our accessories, which I appreciate.
I think to myself: How could I have handled this differently to help the guy with the wine without opening up multiple bottles at my expense?
If anyone has any advice for me, I will gladly consider it.

Tom