It's not ALWAYS, but it is a scam to mine your email address and/or phone.
Hence, the disclaimer I use as a SELLER. Did you read it? It separates the flakes and scammers from true buyers. I don't lose sales and I don't respond to scammers. Simple. Only through craigslist mail system initially. Folks are very understanding. If you offend a scammer or an idiot who can't read, who cares?
I rarely have less than 30 Jeep items on craigslist at any one time and I sell lots.