Cody, no one can guarantee you that. They will probably post under services section which gets little or no traffic.
To post without being flagged is not hard, just reqires a little time. Here are the steeps. Rotate your IP address every 5 or 6 postings. Use a diffrent email address for every posting (Setup a catch all on a bunch of domains). Do not use .info Do not post the same URL in your ad copys (Links to Images they will see also). Make TONS of diffrent ad copys and subjects to rotate through. I use EasyAdPoster software becasue it will help you randomize everything and it support athenticated proxy servers. Also, I am selling a proxy service you can use for craig's list. You can view our website at exclusiveproxy.com
I think you got spammed by somebody. See second-warning.org domain is not craigslist at all. So I would say don't worry about it.
The system is a bit arbitrary. Sometimes legitimate posts get flagged, too. If you think your ad is unfairly flagged, just repost.