I thought the following passage explained it really well. Perhaps you should pass it on to your less knowledgeable friends.
Sweet wines are most commonly known as dessert wines. Evidently, a sweet wine is sugar-rich and thus contains twenty to twenty five percent residual sugars. On the other hand, dry wines only have 1% or less residual sugars in it that it is almost negligible to the taste buds. Sweet red wines include Pinot Noir, Zinfandel, Cabernet, and Syrah. In addition, sweet white wines are termed Riesling, Chardonnay, Chenin Blanc and Sauvignon Blanc. A dry red wine is a Merlot while a dry white wine is a Brut.
I'm glad I had it explained by a professional. I really understand it now. I think I'll serve one of those Pinot Noirs with dessert tonight.

