Mike is a good presenter and Edd makes most of the repairs look fairly simple, even when they are not! Being a member of this forum, even though they rarely mention it, the cars are much shiner when they are ready for sale - don't know if Edd does it or someone comes in.
BTW, I've read that the 'buyers' are usually crew members or their families. Could be done just to show selling the car within the production time.
I was surprised that they did a one car (a little Suzuki I think) that they could not sell for a profit. It didn't pass the MOT requirements so they sold it for off-roading only.