Schools included on a so-called "name and shame" list by the education watchdog have lost almost 600 staff since 2015, a union has said.
Research by the National Education Union (NEU) found 216 classroom teachers and 133 teaching assistants were among the 599 positions no longer filled over a two-year period at 124 schools highlighted by Ofsted, according to the Government's own workforce figures.
More than 500 primary schools and about 200 secondaries have been judged as requiring improvement or being satisfactory at their last two inspections, according to the report released this week.
Of those inspected this year, 124 schools failed to record a good or outstanding Ofsted inspection since 2005 despite receiving "considerable attention and investment".
Kevin Courtney, joint NEU general secretary, said: "Ofsted's chief inspector says that no child should be cheated out of the future they should and could be aiming for - the reality is sadly very different.
"Putting out lists naming and shaming these schools is neither fair nor helpful and can lead to difficulties in recruiting and retaining teachers - something that Ofsted and Government need to address.
"It is clear that the 'support' these schools have received is not working and raises a significant question about the effectiveness of the current inspection regime.
"The real needs of schools serving different communities will not be met until the Government conducts a comprehensive and objective assessment of those needs and fully resources them.
"This will require reversing the vast cuts that have occurred."
Mr Courtney said the schools had "some of the most deprived children in the country", with 43% of their pupils identified as being eligible for free school meals - considered a key indicator of poverty - in the previous six years, compared with the national average of 26%.
The Ofsted report found that overall education and care provided to young people is "better than ever", with about 90% of primary schools and 79% of secondaries rated good or outstanding.