As a visitor, the downside to ignoring anything that even smells of spam is very low. You might miss out on the occasional real post. If you're Craigslist, ever

As a visitor, the downside to ignoring anything that even smells of spam is very low. You might miss out on the occasional real post. If you're Craigslist, every false positive is a headache. User complaints, support costs, vetting, bad publicity.