Canned goods aren't usually a problem - the heating process during canning kills most, if not all bacteria. Bacteria can only get in if there is a hole in the can. The major problem with old, canned goods is if the contents are particularly acid, they'll start to eat through the can and absorb the metals it's made of. Old pewter has a similar effect - if you store or drink certain acidic drinks like spirits or cider in old pewter, certain chemicals can leach into the contents.

Dried foods on the other hand, usually stored "open" (i.e., not airtight) can gather all manner of things and sometimes these cause a reaction.

LTS