e-bag selling questions

What is with all the sellers who won't give up their phone number? Do you want to sell or not? Why don't you keep what it is a secret, and for that matter, where it is too? Hell, you don't really want to sell it do you?

On Ebay, I kinda understand not putting a phone number but the ads on craigslist that say "email me your phone number" get flagged. Also if I gotta click on the ad to see what the heck they are selling I might as well flag it while I'm there.