Here are some tips that you may not be aware of. These should help you to make money on craigslist. if your ads were not as effective as you would have liked them to be. Your ad is good for 45 days. Everyday that your ad appears it is listed lower on the page. This is because new ads get top priority. In some categories, a single vendor will post multiple ads. This is fine as long as they are not for the same business, product, or service. If they are, craigslist will mark them as spam. It is the only way that you will get it to stop.