UPDATE: The bike was terrible. I'm pretty sure it wasn't a Carlton frame, it was just stenciled in the side of the frame.
I couldn't find the co-op place that was selling it, and finally had to call somebody and ask where it was. When I got there, it was a sketchy basement bike shop, with way too many bikes to have been all donated.
The tires were almost completely dry-rotted, although the bike was billed as "ride ready", the frame has an incredible amount of rust on it. it looked like it was a black bike spray painted white.
so all in all, i just wasted an hour or so, although thankfully no more money than the gas it took to get there.