Well, dude, you go right ahead and believe what you want. It's not like I've never been to E3 or trade shows or a press conference, man. I know that the corporations behind them spend serious money to have themselves and their product seen in the best possible light. They wouldn't spend the money if they couldn't ensure that for their messaging. They'll show you trailers and footage that beg no questions about authenticity if presented right. Those same people could also choose to not let anyone play those games anywhere on the floor nor in private meeting rooms or hotel rooms offsite. Does anyone's flag go off about that? Maybe, but because there's no way to compare personal experience with what they show you, there's little momentum to go on. So, something gobsmackingly amazing might be shown in trailer form at E3, like The Last Guardian. Are you questioning the veracity of the claims made by such a showing? Are you calling Team ICO and Sony full of shit for deceiving people because they offer no way to play or view this title otherwise? No, probably not. And why? Because you extend them credibility for whatever reason. You believe them to be honest despite it quite possibly not being real footage running on a PS3. Even given Sony's past with claiming certain CG trailers were realtime footage running off of a PS3. You extend them your trust. It's implicit in the way you decide not to get all up in arms about it online on some gaming forum.
Now, for MS, they also wouldn't commit a true act of deception if they were going to allow any of tens of thousands to freely film, demo, and talk about their own experiences with those same pieces of software and hardware. In isolation, you have a point about dishonesty if those staged demos were the only way someone could have tried and seen them played...the reality, however, is that they were available to any showgoer and those same folks can and did post their impressions and footage to the internet where millions of people (more than who watched the conference) read, listen, and view those unvarnished experiences and opinions and that is going to directly compare to what the MS conference showed. Would MS spend all of that money on a really long and boring conference to fool some people for a day if forever after they have hundreds and thousands of contradictory impressions and footage show them up? What did they gain from that except a PR disaster of exposed and true deception? So, you're free to believe as you do just as I take a pragmatic approach to the reality of the situation.