Faucet owners are especially dependent on ad revenue. It’s not just income,
you’re paying out money based on the expected income, so you will be actually losing real money if someone is stealing your ad spaces.
About a year ago I installed the bitter.io extension so I could use the Paid to Click site and get some Satoshi. I noticed after a while that all the pages I was visiting had the same ads. This went on for some time and eventually, I narrowed it down to the new extension.
I wrote to the owner and he quickly issued an update to fix it. Leaving aside such disturbing questions as “how can you do something as complex as replacing all the ads on all pages I visit with your own ads by accident?” I carried on my way.
I recently came across an article on the Wordfence blog which explains how such things are done, and how it can be done also by hi-jacking legitimate extensions written by others. More importantly, it tells site owners what they can do about it.
Read more at wordfence.com