It's a terrible violation but Ebay doesn't do anything about it. I find description searches to be vital, so I agree with you that turning off that portion is not acceptable.
My solution: I take the most extreme item that routinely runs in such descriptions and add it as an excluded term in my advanced search (which I then save). For me, when searching for coins I often get a lot of challenge coins in my search that include the term "not NYPD" so they can get all the NYPD collectors to look. I add "NYPD" as an exclusion so any conforming search that also includes that level of spam is automatically removed from my search results. For you, perhaps an obscure casino that is mentioned every time - but never produces a fruitful result for you - can be selected.
I have complained to Ebay in the past about spam. If it is marginally related to the topic, they don't take action. If it's for stuffed toys and they keep repeating terms like "NYPD," I think I have seen results - but as you know, Ebay does not report back.