Okay, took another chance and bought a 4 pack of Sutter Home Chardonnay, was only $6 at Stater Bros. It's not terrible, basically just a flat Brut Champagne, and it's the same alcohol percentage so I guess the bitterness was from the tannins and not the alcohol itself.
Still, nothing to write home about, and if I'm going to have this I may as well just get champagne, since the carbonation makes it so much better.
Works well enough as a Mimosa though, without the carbonation. I can drink one of these on occasion, I suppose.