Incoming Ofsted chief Sir Michael Wilshaw has called poorly-dressed staff "patronising" to schoolchildren.
In an interview on BBC Radio 4, Wilshaw said teachers should be obliged to wear smart clothes to schools.
"It's patronising to children for staff to dress poorly. I would expect all schools to think about the way staff dress and ensure they are dressed professionally," he said.
But his comments provoked debate on social networking sites, with one person tweeting: "Define 'smart'. Then define 'subjective'. I seriously suspect our Dear Inspector would fail by the standards I set myself for teaching."
During an interview with BBC reporter Michael Buchanan, Wilshaw also attacked the current system of rating schools, adding he wanted to rid the "satisfactory" level used in Ofsted reports.
"I've never liked that word satisfactory because it often doesn't mean satisfactory at all, it means far from it.
"There's the 'outstanding' grade which is obvious, there’s the ‘good’ grade which is obvious but when we get further down, we need to look at whether the school is improving or not, and those schools that haven’t got the capacity to improve, and make a judgement to which is which."
Agreeing with Prime Minister David Cameron on the issue of "coasting schools", he said there were "too many" which were "not adding value to children's education".
"Ofsted has to look at that," he added. "Ofsted has got to look at a school, look at its performance levels and make judgements on whether that school is achieving well or not. If it is a coasting school and it's not adding value then Ofsted needs to say that very clearly."
Wilshaw also emphasised the importance of strong leadership within schools if they were to improve.
"Leadership is absolutely key, especially now we've got an increasingly autonomous system in our schools.
"A good leader identifies those people [who want to improve schools], supports them and builds upon them. What we need in this country are more outstanding leaders to take charge in increasing the autonomy of the system."
Wilshaw's comments on teachers' attire are reminiscent of those made by Conservative MP David Shaw in 1996, when he argued teachers should set a good example to their pupils through the manner of their dress.