Members and Charter Members do not see ads on the message board, but that only applies to the message board. It does not apply to the main straightdope.com page. Everyone sees ads on the main page (unless you have an ad blocker of some sort, obviously).
The folks in charge of the web page don’t hand-pick the ads. They go through an ad broker and that broker determines what you see.
Ads these days are usually targeted. If you are seeing right wing clickbait ads, it’s because the ad broker’s algorithm thinks that you might respond to right wing clickbait ads. Ad brokers usually don’t publish how their algorithm works, but it’s a safe bet that they are using things like your IP address, browser history, search history, and any cookies that might be set on your computer to determine what ads you see.