What is going on @ Craigslist postings?

[VOLKAN B]

I have recently posted couple of of my electronics for sale. I am having so many fake/scam replies.
These people are really professional and acting like a buyer and asking "is still available" "I will pay cash" "i can come pick it up tonight" kind of emails. When I put my text # they also text and act like a real buyer but I KNOW THEY ARE NOT BUYERS. They are polite and always use similar phrases.
Sometime 5 minutes after posting I receive 4-5 e-mails for a stupid old Iphone 3G....and emails continue throughout the day. I tested to post 3-4 different category items and result is the same , they are targeting everything in CL not only electronics.
I was wondering who are these people and what is their goal? I am thinking that they may be working for Ebay and trying to annoy/scare craigslist community since they are the only competitor. They can't be CL's employees trying to promote their site with annoying sellers.
If you guys have any opinion or other scenarios why these fake buyers are acting very professional. They look like they are doing this as a full time job. WHO THE HELL ARE THESE PEOPLE.

[Kittysue]

They are professional thieves who respond to anything of value listed on Craiglslist - especially phones, laptops, games consoles and designer goods but honestly they don't care as long as it's something they can resell
Their goal is stealing your item by sending counterfeit checks/money orders or paying with hacked Paypal accounts hoping you will ship out the item before the check bounces or the paypal account holder reports the theft. Then they resell your item for cash
Craigslist is ONLY for face to face CASH transactions of you will always be scammed and lose your money and your item

[Roddy]

Are you aware that eBay owns almost 25 percent of Craigslist? They aren't likely to do damage to their own investment. As the other answer suggested they are just plain scammers. Almost any electronics will be targeted by them.