Tough though it is on those who do them, certain occupations have become synonymous with failure. Probably no one presents themselves to a careers teacher and says: "Sir, what I really want to be is a dustman." It's a job people end up in, having tried other things and not succeeded.
Dressing up the job description to seem like something better doesn't help either. You may call yourself a refuse collector or sanitary operative if you like, but dustman is still what others hear.
You could say much the same about other jobs. For all that it says "excrement executive" on your passport, to the world you are a lavatory attendant.
Sadly, to this short list of "failure" endeavours we must add teacher.
Now, you might think that all those glossy recruitment ads had knocked that old image on the head, portraying teachers as saints - or at least worthy folk who go to bed content that their day's work has contributed to the wellbeing of others. But not a bit of it. Somehow the old perception of teachers as amateurs, and teaching as a profession you end up in when all else fails, persists in the public consciousness.
I was reminded of this recently when watching a production of Tracy Letts' play August: Osage County. This is not some creaky old thing from the 1930s or '40s. It was first produced only two years ago and is still drawing in huge audiences all around the English-speaking world.
The offending reference comes early on in the play, when former college lecturer Beverly Weston looks back on his life. As a young man, Beverly published a slim volume of poetry that some people thought rather good. As such collections normally sell about 10 copies - half of them to relatives of the poet - that doesn't really amount to very much.
For the next 40 years he had a successful career, enthusing young people about his subject, which we presume is literature. But because the slim volume wasn't followed by a second slim volume - no doubt to be read by 20 people, half of them close family members - Mr Weston deems his life to be a failure. He takes to the bottle, goes out in a boat, jumps in the lake and doesn't bother to swim.
Maybe there was a time when people did drift into teaching because they couldn't think of anything else to do. However, when I look at my colleagues today, what I see in most cases are not so much failures as successes.
In further education in particular, people come into the job to pass on the art or craft they have mastered in the outside world. What use would you be at showing someone how to cook, cut hair or fix a faulty engine if you couldn't do it yourself? And many are prepared to take a cut in pay for the privilege of doing it.
This was highlighted in two recent reports into FE recruitment, where staff were asked about what attracted them to the profession. Far from chasing money, people were making a positive choice to pass on their skills to others. They wanted to make a difference, they said, in a human way that wasn't always possible in the job itself.
Maybe we should be blaming George Bernard Shaw for the perception that teaching is a sort of retirement home for no-hopers. In 1903, a character in his play Man and Superman comes out with the maxim: "He who can, does. He who cannot, teaches."
Over the years this has more usually been rendered as "Those who can, do; those who can't, teach" - perhaps reflecting the fact that large numbers of teachers are not men but women.
At some stage a wag - no doubt a disgruntled teacher - added the corollary: "Those who can't teach, teach teachers how to teach."
But what about those who fail even at that? Maybe they can still enjoy careers as sanitary operatives or excrement executives.