Compared with the cold, impenetrable fortresses of Wall Street, tech firms project an image of being more like bouncy castles – approachable and fun. This easy-going reputation, a remnant of Silicon Valley’s early days, is as out-of-date as a typewriter. These companies are desperate to control the media’s narrative: they go to great efforts to keep tabs on reporters like me, whose job it is to keep tabs on them.

Journalists often tape interviews to keep an accurate record of what was said. In Silicon Valley, the PR staff make their own recordings, even with off-the-record chats. Companies compile lengthy “dossiers” on journalists, including cuttings from articles and notes from employees who have met them. I’ve done interviews where my file, including photograph and detailed notes, has been left open on the table – possibly deliberately. A journalist I know dialled in a few minutes early to interview an executive at one tech giant, only to hear them reviewing her file, unaware she was on the line. She was relieved to learn that she was in the company’s good books.

Tech companies categorise reporters depending on what they’ve written. Those who’ve said positive things about the firm are grouped into the “friendly” cohort, and are the first to be planted with stories. Ones who alternate between taking swipes and reporting good news are known as “independents”: strong-willed and uncontrollable. Then there are the “untouchables”, journalists who have written even mildly critical things that the company boss has taken issue with. Just as Donald Trump’s White House excludes some journalists from press briefings, tech companies blacklist “untouchables”, banning them from attending product launches or interviewing executives.

Depending on which company you ask, I am either independent or untouchable. But I have the luxury of not needing to care too much about my label. The career of some journalists who cover only one or two big companies depends on breaking news about them, so they have to balance their journalistic scruples with the need to avoid appearing overly critical.

I have rarely in my career encountered so much secrecy. Sometimes a PR person emails to gauge my interest in writing about a company even before revealing its name or exactly what it does. I have interviewed startup founders who refuse to disclose details about their business model. This kind of stealth hampers public accountability. Firms that are unwilling to share details about their technology have been known to lure journalists into overhyping their potential. The media dubbed Elizabeth Holmes at Theranos the “next Steve Jobs”: she sat for interviews and photo shoots without ever revealing many details about her firm’s technology. Earlier this year America’s securities regulator charged her with deceiving investors.

When visiting tech firms, reporters are asked to sign non-disclosure agreements on iPads as they check in. I used to remind the receptionists that the very purpose of my visit was to disclose information, but they couldn’t care less. After they let us in, most tech companies make us wear badges around our necks to alert everyone to our presence (danger! Journalist on the loose!). At Facebook, the lanyard is red. It feels like a scarlet letter.

Another quirk of the tech world is press dinners, often at booked-out, Michelin-starred restaurants. After starting on this beat, I did what any curious journalist would do and accepted a host of invitations, wondering what sort of scoops they were serving up. The answer, in my experience, is none. Top executives tend to be as perfectly scripted as the lead character in a Broadway play. Once I drove to Palo Alto for what had promised to be an intimate off-the-record dinner with a top brass, only to find 25 other hacks there. The executive was so guarded that she looked to her PR person to answer even basic questions on her behalf. I left before dessert.

These swanky dinners (one invitation promised a “multi-course dining experience of artfully presented French dishes with a focus on innovation”) are a form of gourmet bribery, a flambéed carrot to lure hungry journalists. Even tiny startups feel obliged to splash out. Plenty of articles trace their origin to these meals. But to reveal the story of how Silicon Valley treats journalists would be seen as biting the hand that feeds us.