Well, it seems I was a tad impatient with yahoo... they seem to be making good on my complaints:
Apologies for the inappropriate ads on your group.
Our ad systems are entirely automated and sometimes these systems make mistakes: both in terms of what sponsors are allowed to buy ads and what groups these ads are paired with. We rely on users like you to let us know when these types of mistakes are made.
In any case we are now taking action to remove these ads from your group (we are just getting to this email now, so if one of the ads stopped appearing earlier it was just a coincidence). It usually takes 12-24 hours for these changes to fully propagate through our systems, so you may continue to see these ads for that long. If they continue after that, please let me know.
Thank you for bringing this to our attention.
- [name deleted]
Yahoo Groups Team
I have to give the guy credit for this very polite reply to my rather [er] strident complaint. I'm not sure if he got the entire message, tho, so I sent him this:
Thanks, [name deleted]. I appreciate your attention to this matter.
If you're at all interested in why I was so incensed about these innocuous-looking ads, check out this book: The Natashas: The New Global Sex Trade by Victor Malarek. It's available at Amazon and you could also get it at the local library (perhaps on interlibrary loan).
These "companies" are not as innocent as they look. They live off the avails of prostitution, and they trade in human misery.
Thanks again for cleaning these disgusting ads off my site.
So, that's done then. I fully expect those ads never to appear on my list-serv again.
I do sincerely hope yahoo also considers it a mistake to allow such "sponsors" to buy ads on their service. I'm not, however, as confident about that.