Botulism has a few requirements before it can grow. It requires a moist, low acid environment with low oxygen. Dry beans are safe as are all dried foods. Canned foods, because of being moist and low oxygen could be ideal environments. That's why the foods are either acidified by adding citric acid, ascorbic acid (vitamin c) or some other food acid, or are canned at high enough heat (pressure canning for soups, meats, etc) that the botulism spores are killed.
Botulism produces pressure, so if a can is bulged, avoid it. Also, heat breaks down the botulism toxin. Cooking canned foods for 10-15 minutes would break down the toxins, but it's better to avoid any suspected foods and not take the risk.
Are you sure that heat will denature botulism toxins? Any sources for that?
