CL users flag postings they believe are inappropriate by clicking the "prohibited" link near the top of each posting.
Free classified ads sufficiently flagged are subject to automated removal.
Forums postings and paid classified ads sufficiently flagged are subject to further review.
Postings may also be flagged for removal by CL staff or CL automated systems.
Of course no moderation system is perfect, and a small percentage of ads removed are compliant.
Flagged postings that comply with the TOU may be reposted, reworded as necessary.
For help from CL users as to why an ad may have been flagged, visit flag help forum, and follow the instructions there.
Funny or memorable postings may be nominated for inclusion in "best of craigslist."