Deeping St James Parish Council was told the Deepings Leisure Centre, in Park Road, has not had a cleaner for the last three months.
Staff have been attempting to keep the premises clean but it has still failed its last four cleanliness inspections.
Contract cleaners have now cleaned the premises thoroughly and inspectors visited while the work was being undertaken.
The council heard the top half of the centre, which had already been cleaned, would have passed if it had been assessed separately from the bottom half, which was still waiting to be cleaned.
But Coun Philippa Lincoln said she had been at the centre one evening and it was dirty and in need of cleaning.
The council also learned that Leisure Connection, which runs the South Kesteven District Council-owned premises, is responsible for health and safety rather than the council itself.
Leisure Connection will manage the centre until 2008 when the district council will again consider the possibility of a leisure trust taking over its facilities.
A South Kesteven District Council spokesman said the centre had seen a marked improvement.
He added: "It is the highest rate, in terms of cleanliness, the centre has had in 19 months.
"It is now at a point where members of the public should not go in and feel unsafe.
"We are confident the centre can continue to move forward and hope it will once again become a well used premises the Deepings can be proud of."