Christmas Special: Part 2 - S3-E2
Revealing mistake: Many shots show the trees and bushes in full bloom despite the fact it's Christmas. Most notable is the tree outside the pub window in Brent's second date and the bushes outside Brent's window when he's driving around in the daytime. Acknowledged in the DVD commentary.
Answer: In the Christmas specials, David states the documentary crew stitched him up. In other words, he was made to look like an idiot by the way it was put together, but in actuality, he may not have been as bad as the documentary had made out. In addition, it's clear he let his upcoming celebrity status get to his head, something that would not have happened prior to the documentary crew's arrival. At the end of series 1, he mentioned one of his achievements was cutting expenditure without losing any staff.