Who are the students these colleges must cope with? What sort of catchment areas do they serve? And what role do the inspectors play in all this?
A partial answer to the first two questions comes this week from the Learning and Skills Development Agency (page 3). Schools contrive to shift their most difficult pupils over to college. In such cases, headteachers put the prestige of their school before the education of all children. That is the national disgrace.
Equally, ill-advised and apathetic children and parents go along with it.
How much does the apparent success of burgeoning specialist schools rest on such manoeuvring? Remember too that for every 16-year-old shifted from school to college, the Treasury saves an average of pound;1,000 - effectively cutting cash to those in greatest need. Another national disgrace.
What of the inspectors themselves? There are in fact two post-16 inspectorates - Ofsted and the Adult Learning Inspectorate. David Sherlock, chief inspector for ALI, reports record improvements among work-based training companies. But his methods are different from Mr Bell's. When these companies fail, Mr Sherlock's inspectors spend time working with them, advising and challenging them, before re-inspection.
This is not a consultation; inspectors are not doing the training providers' jobs for them. But many private providers work voluntarily and say they would quit the market if treated as Ofsted treats schools and colleges.
Plenty of schools complain that Ofsted's tactics are to go in, hit them hard, never to be seen again. Schools and colleges see no one calling Ofsted to account for its judgements.
Of course, Mr Bell is right in his central assertion: colleges cannot hide their inadequacies behind a veil of policies aimed at widening participation. Genuine failure has to be identified and rooted out. But colleges cannot and should not be viewed in isolation.
The Association of Colleges must answer tough questions when Ofsted's two reports, Why colleges fail and Why colleges succeed, are published next week.
But so must the Secondary Heads Association. The sad fact is that colleges fail most often where schools have the first and richest pickings.