It used to be, the big difference separating movie critics, film journalists and whatever the hell it is I do from the movie-going public was that the professionals would generally be aware of things happening on the production side of what they were watching and would then have to decide how much - if any - of that information should inform their reporting.
Like it or not, knowing about difficulties and issues surrounding the making of a film can color one's perception of the final product, and in the old days, most mainstream audiences were not concerned about the making of films or the goings-on of any filmmakers other than movie stars. So while a celebrity scandal could potentially derail a release ("I'm not seeing that! Did you know she stole him from his wife while they were shooting overseas?"), stories of budget overruns or unhappy producers rarely would.
This began to change with the advent of fanzines in the mid-20th century, but even then it was mostly contained to the realms of technology and genre-fandom. An article about a new creature creator in Famous Monsters could raise the profile of this or that B-movie with a certain demographic of fans, but it still wouldn't make major news, and producers of big movies still wielded incredible power to keep the press out of their business.
All that changed, permanently, with the advent of the internet and fateful bit of PR spin by Warner Bros. When Batman & Robin turned into a then-surprising box office disappointment, some elements of Warners' publicity made headlines by pinning a portion of the blame not on the movie itself but on Harry Knowles' Ain't It Cool News website for posting "leaked" stories about budget, script and production problems that had plagued the film prior to its release. The story put AICN and other film geek gossip sites on the pop culture map, and soon enough "pre-production" watching leapt from being a burgeoning movie-nerd pastime to a full-blown national sport. Tracking numbers, test-screening results, box office prognostication and other movie biz minutiae that had once been the exclusive province of film journos and the hardest of hardcore industry watchers was now being reported in the same manner as football scores and lottery numbers.
All of which means that, like it or not, more and more people wind up walking into movies with questions and baggage both beyond and removed from "Will I enjoy this?". We'll know about actors not getting along, about scenes being hastily re-shot, about directors and writers being replaced/fired, about ballooning budgets and studio worries ... and it's hard not to feel like it's starting to get in the way of just watching the damn movie.
Some films, to be fair, have learned how to cannily turn this situation to their advantage. Avatar practically dared audiences to show up and see if James Cameron really had gone mad with power or if his unprecedented money/tech expenses were worth it. More recently, Joss Whedon's script for The Avengers ingeniously turned the worrying question mark of the film's production - "Is putting guys from 5 disparate movies onto one team actually going to work?" - into the central conflict of the story; hence why the film's iconic "We did it!" victorious money-shot isn't the destruction of the villain(s) but rather the assembled heroes standing in costume on the same street.