I've been patrolling my local Craigslist in spare tiem to remove bots, for a year now. Here is what I have found:
99% of all w4m ads in any given month, are fake (yes, turns out there are some real ones on occassion, but usualy just unattractive overweight girls, or girls who do drugs).
You will NEVER get a REAL response from gmail or googlemail e-mail accounts (that goes for m4m too). Okay, well, out of a 100 you might get one or two.
Just put at the end of your ad a brief line like:
Please put "TrekBBS Craigslist" is the subject line so I know you are nto a bot, otherwise I will delete you
Many Craigslists people do stuff liek that. I will instantly help seperate spammers. 99% of spammers don't read the ad AT ALL. They just send their spam. Don't believe me? Try posting this:
"Hi, I'm a serial killers who has dead bodies in his frezzer. IF you want to die, e-mail me now!"
And watch the replies come in from spammers. However, even with a subject line, you won't stop the persistant spammers who do whatever it takes to try to phish you.
Never put a phone number either. I pity all the folks who do; I bet they get all kinds of spam calls now.
On the annoying opposite side, however, 99% of w4w ads are real. Damnit.
There is also a HUGE number of spam job ads -- including ones that look very real. I'd say in my local job category, about 90% of the monthly ads are FAKE.
And there are about 5% fake ads in the house rentals section.
What Craigslist needs to do is have moderators. I'd get the shit otu of there so quickly the spammers wouldn't know what hit them.