Steven Brill has an article about that New York City institution, the rubber room, which has attracted some attention among bloggers. Rubber rooms arose because firing teachers is an extremely lengthy and difficult process (because of arbitration provisions in their union contract). But they can assigned to rooms where they sit and do nothing (with full pay and benefits) while their arbitration hearings drag on year after year. This is done when the school administration thinks it is necessary to remove a teacher from contact with children. These assignment rooms became known as "rubber rooms" . This process provides a ready supply of horror stories about teachers collecting for pay for years after instances of extreme misconduct. Steven Brill is the latest writer to mine this supply.
On the narrow point I agree with the critics, this process is indefensible and should be changed. I would suggest a no-fault termination system in which the administration could fire anyone with payment of say 2 years salary as severance. However it is not really that important in the whole scheme of things. 600 rubber roomer teachers out of 89000 is less than 1%. So just budgeting for this like you would for sick days is going to increase your costs by less than 1%. Not good, but eliminating it is not going to drastically improve school performance.
Brill suggests the real problem is that the firing process is so onerous that it is generally only used for misconduct and merely incompetent teachers stick around forever. My view is that teachers don't matter much so it is not all that important to get rid of incompetent ones.