In fact - as reported in this newspaper - this crime tops even such cardinal sins as "perving" on students, having coffee breath, or telling bad jokes.
Is it true that teachers have a personal hygiene problem? How many of us are officially in the doghouse of pong? Is there any reason to suspect that teachers have been cursed with bigger and more active apocrine glands than any other profession? Sorry to all you sweet-smelling hordes out there but, at the risk of my pearls falling on stony ground, I have to say it. Some teachers smell and, in some cases, quite odiously.
Stinking teachers naturally invite disdain from their pupils but it's a terrible experience for the kids. They can't respect adults who don't even have the savvy to take care of their own physical needs. How can you take a teacher seriously if you smell them before you see them?
OK. I haven't been spinning a scientific top on this one - just the usual nosing around and asking a few pertinent questions here and there, sniffing for a story so to speak. It would seem that many school staffs have a few stinkers in their midst and that's leaving the smokers out of the equation.
Further, and I know I'm courting litigation, the problem would appear to be a predominantly male one.
A meeting room on a hot day. Everyone avoiding sitting beside a certain person. That individual apparently oblivious to the shenanigans going on around him. Isn't it amazing how you can develop a kind of low gear breathing technique, during which you inhale just enough oxygen to ward off hyperventilation? It's utterly reprehensible that teachers, whose jobs entail a great deal of responsibility, behave in a way which is, frankly, unfathomable.
What this problem amply demonstrates is that there are still some taboos that even teachers find difficult to tackle and telling someone that they stink is one of them. We can preen ourselves on our emotional intelligence, our social skills, our all singing and dancing teaching and learning strategies but, if we are strangers to personal hygiene, we are nothing more than a very bad joke.
But hearken to this tale. A friend, a primary school headteacher, was forced to speak to one of her male teachers about his body odour. Her approach was completely matter of fact. The conversation went pretty much like this. The headteacher said: "You have a problem with your personal hygiene. It is offensive for your pupils and for your colleagues. It can be cured though, given a bit of effort on your part. From now on shower every morning, use anti-perspirant and have a daily change of clothes. I want to see an immediate improvement."
Guess what? She did. You may well ask why a grown man, married and with children of his own, needed his headteacher to lecture him like a newly hormonal adolescent before he took a tumble to himself with his personal hygiene. I rather fear that macho men - and we have plenty of them in the teaching profession - see cleanliness as something which just isn't a priority.
Not that we're looking for them to start behaving like David Beckham - the skirt, the cute wee Alice band, the forever changing hairstyles - but the basic rules of hygiene are essential for everyone. Otherwise our impressionable young charges will despise them and no wonder.
You too can do your bit. Tell your offending colleague that he has a problem. Chances are that you will be pitching for the perfect ear. Trust me: I can smell them a mile away.
Marj Adams teaches religious studies, philosophy and psychology at Forres Academy.