So, what is the definition of a flaker? Someone who breaks a deal to buy something after he makes partial payment or a "tire-kicker"? The first example, I wouldn't call a flaker, I'd call him an idiot. The second, I'd call a flake. Especially, if the person asks you to package it all up and get it ready for shipping. When I ask someone to do this for me, I feel obligated to follow through. So that leads to the question... do flakers deserve negative feedback? I'm usually patient with people and if they back out, I understand so I'd say no.
"Any punk can shoot from across the room but it takes a real man to get close enough to stab"
"Why cause a huge disturbance when you just wanna kill ONE guy?" - Chris Rock