I don’t see any commercial links. Describe exactly what links you are seeing. Post screenshots, if you can.
If they are links that aren’t part of the question or answers, and are simply advertisements like this, then the most likely cause is Futher, as ads are served to people who are not logged in. This helps keep us solvent. Unless of course you were logged in (double check this). If you were, then I don’t know what happened, as it is not Fluther doing it.
If they were links within the questions or answers, and those links give you ads when you hover over them, then that is not Fluther, and could be adware. What web browser are you using? I’ve removed things like this from my own computer, and I could help you, if I knew more about the problem.