These scams have been around since kijiji has been around.
It's not corvette centric, affects any car, whether you're a buyer or a seller. They target cars due to the big dollar amounts involved.
Scam basically goes along the lines of I'm interested in buy/selling (x) car, I am not available because I'm in the army, navy, jail, mental institution, space etc etc, please deal with my (broker/shipping company etc). The scam is when they ask you eventually for a 'fee' to cover delivery/inspection of the car which can be several thousand to a mysterious escrow service.
The things to look out for so you don't waste your time:
1. Pics that don't look right (palm trees are a dead giveaway)
2. Broken English, references to 'Item' as opposed to car (most of the responses are scripted and automated until much later)
3. Price too good to be true
4. Offering to buy your car or sell to you sight unseen
Just exercise common sense.
They always follow the same script luring you into conversation with a sweetener whether that's offering beyond asking price or selling unrealistically low.