Measures to remove incompetent teachers from schools do not work, according to some headteachers.
An estimated 52,000 teachers work in Scotland
A definition of competency was established five years ago to aid councils when asking staff to leave.
Research has found that nine have been sacked in the last five years, while inspectors believe 6% of lessons to be unsatisfactory.
Education Minister Peter Peacock and the Headteachers' Association of Scotland want councils to be tougher.
The nine teachers removed from their positions make up a small percentage of Scotland's estimated 52,000-teacher workforce.
Glasgow City Council was found to have taken action against seven, with Falkirk and Aberdeenshire acting against the remaining two.
Eleanor Coner, from the Scottish Parent Teacher Council, said: "For a long time now we have heard about badly behaved pupils and about parents who aren't looking after their children properly.
"But parents, and others, have been aware that there are incompetent teachers in schools.
"Most of them are very good, but there are incompetent teachers."
The EIS teaching union said powers are available to councils and insisted the vast majority of staff in teaching positions are highly competent.
General secretary Ronnie Smith said: "I think we've got a very high quality profession because it is very demanding and challenging to get into teaching and we have rigorous pre-entry requirements.
"I'm confident that there are very very few incompetent teachers."