You did ask for a response from ME, so I replied.
There is NO "selling" app in existence (OU, LetGo, 5Miles, Mercari, eBay,etc.) that has some sort of system in place that PREVENTS 100% of the ads with keywords to appear/posted.
On OfferUp, the only option to have these ads removed is for users to actively report prohibited ads. If you have a more realistic solution, please do share, but a blanket statement of "keyword heavy posts never get approved"...is like saying people should not lie. If you have an algorithm that can weed out JUST the keywords, please post it on GitHub.
The best current method of "keyword" removal is implemented by CL, in which the the actual community of users can affect the removal of an ad once it hits a pre-programmed threshold count. This is the BEST solution that I have seen and does work.