Hubs do not automatically earn once people read it. The key is if readers are interested in the ads associated with the hubs, whether Google Adsense, Amazon, Ebay etc. However, click fraud is prohibited and HubPages advises against clicking ads from your hubs or the Hubs of others. There is little you can do to influence persons to click Google or HubPages ads, and the Amazon and Ebay clicks are only worthwhile if an order results. However, you can add descriptions and relevant ads to boost the likelihood of that happening.