The chief inspector of schools has accused some Ofsted teams of misleading headteachers about the new inspection regime by telling them that standards had become even more demanding.
David Bell said some inspectors had said benchmarks had "shifted up a grade" since the inspection framework was introduced by the Office for Standards in Education last September.
But he told the National Association of Head Teachers' secondary conference: "That is not what we have done, but we have laid out the criteria more clearly.
"There is also a myth going round that if you fail to satisfy one bit of the criteria you cannot be excellent. That is not true."
However, Ofsted confirmed this week that schools are now graded unsatisfactory overall if 10 per cent of teaching is unsatisfactory. Until last September, that figure was 20 per cent. Mr Bell tried to clear up confusion over the new framework but sent out mixed messages on the acceptability of "satisfactory". He said inspectors' judgments must be made in the context of the whole school.
"Satisfactory does mean that it is an acceptable level of competence," he told the conference at Warwick last week. "But it may not be a sufficient driver to generate the kind of improvement schools need to make a difference."
Mr Bell also questioned the need for GCSEs under the new 14-19 exam system proposed by Mike Tomlinson, his predecessor .
"If we are trying to promote a view of education 14-19, we need to think about the impact of assessment of age 16 which seems to reinforce the concept of a break or end-point, rather than a staging post ," he said.
Mr Bell's comments came at the start of a week in which he appeared before MPs, spoke at two London conferences and was grilled on-line by heads on the National College for School Leadership's website.
His speech to the Fawcett Society on Monday called on the media to provide more strong, female role models such as Buffy the Vampire Slayer (see story below).
An appearance before MPs later that afternoon was more sober. He warned that "satisfactory" local authorities may also need to raise their game. Mr Bell said councils could face tougher inspections, but any change would come after Ofsted takes on the job of checking children's services set out in the Children Bill.
Today he travels to Birmingham for the Education Show where he will call for a substantial rise in the number of teachers trained as inspectors. At present one in five inspectors is a teacher, and most of those are heads.
Mr Bell said teachers would improve their leadership skills and that inspections would benefit from having members with recent teaching experience.
He conceded that he would face charges of "dragging teachers out of the classroom" to carry out inspections, but this should be balanced by the benefits to schools.