Line item properties play an important role in many stores and product workflows
Sometimes you want the customer to see this information alongside the line item, but often you don't
Take the case of tracking promotion items added via a script and identified by setting a line item property as an example.
Luckily Shopify makes it easy for you to hide properties on the cart page by prefixing the name with an underscore
But it's still up to you to modify your theme code to ensure that those properties are not displayed on the product form
Here's an example code snippet showing how to reliably detect properties that should remain hidden.
﹛% for p in item.properties %﹜
﹛% unless p.first.first == "_" %﹜ this is not a hidden property ﹛% endunless %﹜