Forgive me for not using your name, as I was not given it.
You are an employee of the US embassy in London. Your job is to take the form DS-156, which gives the embassy information about who is applying for a visa. You are not approving the visa -- that's handled beforehand. You are simply making sure it's dished out to the right person, and doing some perfunctory checks to make sure that person isn't a terrorist, with a form that asks subtle questions like "have you ever attended a madrassa?".
Nevertheless, you have a certain petty power. You can render the appointment invalid, forcing the applicant to re-book, a process with a 6-day waiting period, thus ruining their travel plans. It's tedious and expensive.
So today, when I handed my forms to you, I was nervous. I didn't want to have to extend my trip -- I don't have any vacation left, so I can't -- and the forms are big and scary. You could have been understanding and kind about this, but instead you chose to be a dick.
DS-156 asks for your current address. Nowhere does it say "this address must be outside of the United States". In fact, when filled out electronically the USA is in the country drop-down, which pretty clearly suggests US addresses would be valid. Since I live in the US, I put my real address in San Francisco. You took issue with this, saying it had to be in the UK. When informed that I didn't live in the UK, you rudely told me that "you have to maintain some ties to this country". Is your implication that having lived in the US for 3 years, I should be paying rent somewhere in London? Perhaps you missed the bit on my form where it mentions that I was not born in the UK, which is strange since you were so good at spotting everything else.
Your similar objections to US phone numbers for personal, work and mobile phones are similarly nonsensical. I work in the United States: that's what the last visa, which I've had for 3 years, is for. That's what this new visa is intended to allow to continue. Why would I have a non-US work telephone number? How could I?
You also objected to my answer to "how long do I intend to stay in the US" as "indefinitely". Given that my current visa can be indefinitely renewed, and that I honestly don't know how long I intend to stay in the US, this is an honest and accurate answer. Your objection here was particularly irksome given that I gave exactly that answer on my previous DS-156 form 3 years ago and it was accepted without complaint.
Finally, you objected to my passport photograph, when you asked how long ago it was taken and I answered, again, truthfully, "January". You said "that's no good". When I asked why, you initially replied "I just don't like it". When pressed, you said that it must be within the last six months -- fair enough, this was a rule I had missed. Obviously I could have just lied: it's not like my appearance has changed drastically since January. But again, your strict adherence to a nonsensical rule stood out.
Finally, while flustered by your blizzard of objections to my form, you told me to "come back here when all that's fixed". You didn't specify whether that could be later the same day, or that my appointment had been cancelled. Instead, you said -- and this is why I'm writing this -- "you need to leave now", and then refused to answer any further questions.
I understand that you don't have the world's most fun job, and that you get bored of the same confused people making the same mistakes on the same form hundreds of times a day. I sympathize. But the correct response to this situation is not, I suggest, to imply that I should lie on immigration forms just so they meet illogical rules, nor is it to rudely leave me without clear instructions on how to complete my highly important visa application. In fact, I think refusing to answer my questions about the process constitutes a dereliction of your duties, while your rudeness and generally hostile tone of voice were merely unnecessary.
I would leave with the impression that this is merely the way the US embassy in London works, were it not that the second stage of my interview was handled quickly and professionally, with a friendly smile, as was my entire previous application process.
So congratulations. You used your minor authority to scare the shit out of a nervous man who had got a few boxes wrong on an almost totally pointless form, and wanted nothing more than to come to your country, do work they cannot find any Americans willing to do*, and pay taxes. I'm sure there's some good and noble reason you thought that was the right thing to do, but just now I can't think of it.
(To everybody else: after several hours delay, I got the visa.)
* Despite 10% unemployment, there are no Americans willing and available to do my job -- it's a legal requirement of the visa.