The failure rate of England's further education colleges is "a national disgrace", the head of watchdog Ofsted has said.
Mr Bell describes a "north-south" divide in college quality
David Bell, writing for the BBC News website, criticises "unsatisfactory" teaching and leadership by principals.
According to Ofsted's figures, 37 of 308 FE colleges (12%) have been judged inadequate during the last three years.
The Association of Colleges accused Ofsted of "bias" and said Mr Bell's comments were "highly inappropriate".
Mr Bell spoke out as he published two reports: Why Colleges Succeed and Why Colleges Fail.
They say that nearly three times as many colleges are failing in the south of England as in the north - all general further education colleges.
Almost one fifth of colleges in the south, and 12% nationally, are failing. Eight per cent are judged to be "outstanding".
The reports' findings are based on evidence from inspections of 308 general, tertiary and sixth form colleges in England inspected in the three-year cycle which began in April 2001.
The area south of Birmingham is home to 29 - or 80% - of the failing colleges.
Mr Bell points out that no sixth form colleges have been deemed inadequate.
Many of the young people who stay in education after 16 but do not take A-levels - such as those on vocational courses - are described as "floundering".
In his article, Mr Bell says problems with colleges are not getting adequate attention, with the media preferring to focus on entry to Oxford and Cambridge, he claims.
"Could it be, I wonder, the influence of the chattering classes?" Mr Bell asks.
"Could it be that the grander elements of the media have little knowledge of, or interest in, FE?"
Meanwhile, higher wage costs in the South mean colleges have more difficulty attracting good staff, Mr Bell argues.
This has contributed to the "north-south" divide in quality.
He writes: "The rate at which colleges are found to be inadequate is excessive.
"A degree of polarisation is happening. The good colleges are getting better and better; the weak are continuing to flounder.
"If you happen to be a 16-year-old looking for a second chance, having not done very well at school, tough luck.
"If at first you don't succeed, you don't succeed."
A "coincidence of political will and a groundswell of public concern" would be needed to improve colleges significantly.
But the chief executive of the Association of Colleges, John Brennan, said he had repeatedly urged Ofsted to reconsider some of the "bias" in its inspections.
He said they favoured academic provision and failed adequately to measure the way colleges brought on their students - the "value added".
"It is inappropriate for immoderate language of this kind to be used about a sector which achieves remarkable success in the face of continuing government under-funding which is severe enough to affect the experience offered to many learners, despite the superb work of staff and managers.
"This is the issue which the chief inspector should rightly be speaking out about."
The Further Education Minister, Kim Howells, said: "Quality overall is improving in further education with rising success rates. There are some very good colleges but the quality of provision is still too variable.
"We are working with our partners to support colleges and providers in improving the learning and skills sector, in line with the Department for Education and Skills' five-year strategy."
Paul Mackney, general secretary of lecturers' union Natfhe, said: "Many lecturers are leaving because salaries have still not caught up with those in schools.
"Most struggling colleges are in the south, where poor college pay is most acutely felt, amid higher living costs, but recruitment and retention problems are nationwide."
Shadow education minister Chris Grayling said: "It is hardly surprising that so many colleges are struggling when all too often they are treated as the poor relations of the education sector, when they are expected to sort out the failings of the school system and when they are being deluged with often contradictory government initiatives."