Check for rust in the bottom. If none is found it might just be the beer. Once in a while I get a batch that taste like bottle caps(maybe you have to be old to know what that taste like since BC seals have come a long way). This was always strange because I don't bottle. To make sure your kegs are oxidized correctly clean them with a sponge, no scrubbies. Swirl some starsan around in them. Dry them by turning them upside down to drain and let them sit there for about a week. It's the Oxide barrier that makes them stainless and the oxide process can be sped up with an acid solution like starsan. Never use anything abrasive to clean them with after this of you will remove the oxide barrier. Hope this helps
auses for Revvy to chime in..:
