MultiStore - How can I find how what shop(s) my product exist in?

You can find out which shop(s) a product exist in via the panel called Multistore Sharing Manager, in the Property column (right handside): the option 'Present' will be ticked.

You can also see which shop is set as default: radio button in the 'Default' column.

In this panel, you can also visualize if the product is active or not in the associated shops: 'Active' will be ticked/unticked