Foreign citizens who travel to Sweden for agricultural and building work live in some of the lowest standard accommodation of all workers, often dirty and posing a health risk.
Official inspections were never made or rarely carried out in half of the 200 municipalities that answered the survey.
Many local councils said they did not know where guest workers lived and that they lacked the resources to carry out regular checks.
One in seven councils that did make checks in the past two years said they found foreign workers living in unacceptably poor housing.
In some cases farm workers were reported to be living in cellars with barred windows and builders were said to be staying in warehouses without access to running water or heating.