How to tell if paint is bad:
Check the paint after thawing. Freezing does ruin latex paint, but it can survive a few freeze/thaw cycles. Allow the paint to slowly warm up to room temperature, then stir it well. If the paint color and consistency appear normal, then it should be all right to use. If it looks like cottage cheese, it was frozen too long and you should let it dry on newspaper in a safe place, then put it in the trash.