Lakzilla, I have had alot of success with craiglist of late. The best advice I can offer is to mixup your adds. They will flag your ads if they are anywhere close to simliar. Make sure to use multiple email address. Try to wait a week to resubmit the same add. Hope some of these tips help!
Im not sure how effective they are, but there are autoposters (+/-$100) that create tons of email address and post hundreds of posts at a time. I now that craigslist is pretty sure at stopping this type of spam.