Not being entirely sure of this, I'm gonna throw it out there anyway...
I *assume* the "scanning scammers" are scanning through the e-mail addresses contained in the ad bodies themselves, not through any tables contained elsewhere on the website.
If this is correct, the easy to avoid receiving these scams is to add _nospam_ or _remove_ or similar phrases to your email address posted in the ad. Be sure to include reply instructions for the less internet savvy.
Andrew
