I never set out to be a copywriter. It happened when I was looking for a job following graduation. And it happened because of something daft - I'd had a wisdom tooth removed, and was in pain for a few days afterwards, during which time I was knocking back whisky and painkillers. Which explains why I wrote a job application in the style of classic detective novelist Raymond Chandler. That in turn attracted the attention of an agency called Christian Davies in Hertford, and pretty soon I was a copywriter as a result.

Turns out Christian Davies was one of the names used by a woman who posed as a male soldier in the 18th century, so the name was a good clue to the fact that I was entering a world where deception was commonplace. And so it turned out to be. This was the late 1980s. There were tales of business won by agencies turning up to pitch with new cars that the client was told would be theirs if they were awarded the account. All of this was eye-opening for me, and what clinched my desire to move was shitty behaviour on the part of one of the agency's directors. His co-director Tim was off ill. And while he was away, his colleague took time to ask each member of the agency for their loyalty during the difficult time - oh, and Tim's a great guy etc, but have a look at these expenses he's running up. Tim died a few weeks later, leaving behind a wife and children. Now, I wonder if the guy who wanted to exit him knew that Tim was dying and wanted to avoid a payout to his family.

Though I tried to find other work, eg in publishing or with the BBC, I had no luck. So when I was headhunted to join a London agency, I figured I might as well go along with it to get away from what was happening in Hertford. It couldn't get any worse, surely...

It didn't get worse. Just - different. For the first couple of weeks, I learned about this new agency, its team and clients. And was shown work that had been done to get me used to how they did things. A lot of their work was recruitment based, ie job adverts. So when a thrusting young director showed me some work that took the form of leaflet to put through the doors on behalf of a high-end department store, I asked why they were doing that and not putting an ad in the local paper. He answered simply, "We tried that, but the ethnic response was too high."

I knew he'd said something unusual, but it took a minute to process what he'd said and translated it into what he meant, which is that too many black people had applied for the jobs. Like there was an OK number of non-white applicants which had been exceeded. Hence leafletting a posh suburb where house prices filtered out any inconveniently-coloured candidates.

That was pretty much the moment I realised that me and advertising were never going to get on. I knew there'd be no smoking gun document about the blatantly racist conduct of department store and ad agency, otherwise I'd have passed it on to people who could publicise what had happened. I can easily imagine the dynamic young director and the client having their conversation about what they needed to do, all about the brand of the store, which wasn't in tune with the job applications they were getting, neither of them even half-conscious that they were engaging in racial discrimination.

Ugly as those experiences were, I'm glad they happened. My eyes were opened to what goes on in a very direct way. And that experience has shaped and continues to shape choices I've made since.

What's interesting to me is what people will do on behalf of a business in the name of making money. And one conclusion is we don't need to be given orders to behave in despicable ways. Our ability to act on behalf of an organisation is something we internalise. A company itself cannot act, but the values it enshrines can become behaviours when they're embraced by employees.

Fortunately, there are lots of decent people out there acting in the name of companies with an ethical outlook. But I remember too the experiments Stanley Milgram did, which showed that an alarming number of people will go along with what someone wearing a lab coat asks them to do, up to giving a stranger a potentially lethal electric shock. OK, so it wasn't a real shock in that experiment, and the stranger was an actor in cahoots with the scientist. Similarly, it doesn't need to be a real lab coat - someone in a suit who has an imposing job title can have the same kind of influence.

I'm lucky in that I have nobody else to provide for. If I choose not to work for a particular client, that's a choice I can live with. For people with families it's trickier. For single parents, even more problematic. There's no one size fits all answer. It does help to acknowledge the questions that come up though, and if none of those questions are coming up in the course of your work, you're either lucky, or need to look closer.