Are you using chrome and also have either uBO-Extra or Nano Defender installed? If not it's most likely the ads are being served by Instart Logic. [1] [2]
> What is the trade-off for not being included by default in the main extension, CPU?
gorhill's (developer of uBO) explanation from[1] below:
> uBO-Extra is needed to deal with IL stuff because the IL inline script appears at the top of the served HTML page -- before any other secondary resource-pulling tag.
uBO-Extra injects its content script declaratively, i.e. on every page, hence it will always run before IL stuff.
The root cause of why it is needed is because of a bug with web socket implementation in chrome.[2]
Additional info on why both are needed (& why for chrome but not firefox) in some reddit threads.[3][4][5]
BTW, I manually blocked the Ad column in CNET & seems to work.