How do you tell if pickles/cucumbers have gone bad We're in the process of making 4-day sweet gerkins and after the second day of soaking overnight the brine solution was foamy and has an unpleasant odor.  Does this mean the pickles have gone bad?
It certainly sounds like they have gone bad yes. A bad smell is a dead give away. As with any such situation, a few cucumbers (or whatever you're unsure about the safety of eating) are not worth getting food poisoning over: if in doubt, throw it out.