When it gets in the way of effective collaboration. The way Dustin wrote his letter, he portrays himself as someone who isn't interested in his client's input. AA might have valid reasons for designing its site that way, based on years of being in the airline business. Even if he's written off AA as a potential client, he shouldn't alienate all potential clients by appearing so opinionated. What if he had picked one of my websites to bash, without asking me why I'd made certain decisions, proposing his own reasons for those decisions, or at least reaching out and being civil? I wouldn't be too happy at all. I'd have to waste time formulating a public response and managing my image in the face of an unprovoked attack.