Problem #1 on CL is people flaking out on you.
Problem #2 is low ball offers.
Problem #3 is people showing up to buy then telling you they have X amount of dollars and that's far lower than your asking price and that's all they got.
Problem #4 is it's hard to get decent prices selling stuff on there because everyone wants to pay pennies on the dollar for stuff.
Problem #5 is potentially getting robbed or worse.
I tried to sell my PS4 at launch on CL and couldn't get a serious offer for anywhere near what it was worth. Craigslist is a buyer's market where buyers have all the power and they'll starve you out until you sell dirt cheap. When I go on CL to buy something I'm not looking to pay what it's worth I'm looking to pay bottom dollar for it.