Most professionals will have a portal they access for information that is behind a paywall. The ones I know of do have some ads, mostly industry specific and fa

Most professionals will have a portal they access for information that is behind a paywall. The ones I know of do have some ads, mostly industry specific and fairly relevant though. Other than this, AFAIK, most other sites behind a paywall serve you as many regular ads as their free to access peers do. I guess having paying customers just isn't enough even for established and respected sites with huge traffic?