E'tac paints seem to have near infinite shelf life, as long as they're kept at a reasonable temp. I still have the old 4oz. "widemouth" bottles in a few colors. Still works perfect.
Wicked and Wicked Detail seem to vary by color. I have some old bottles I've been working through, and some of it works as well as it ever did, some are full of wonderful little dried chucks that clog my airbrush, some are goo...