Compare with current auction reports or price guides, and see how the return is handsome. These are higher risk, and sometimes higher returns. You can make money, but you can also lose. Also, keep in mind that selling these bottles requires an auction and a more limited crowd. Some lady was showing me her garage full of aqua Ball Mason Jars last year, and asked me what I would pay for them.
Some common themes seem to run true when assessing a bottles worth.
Cracks, large chips, holes, usually mean the bottle loses most of its worth. Less severe flaws such as small chips, minor hazing, bruising are not as problematic, especially if the bottle is very rare. The older the better. Not many ABM bottles are sought after with a few exceptions. Safe Bottle is a good example of a bottle which is attractive, old, and for sake of argument, say its perfect.