This was written by Annie in response to a question about birds having mites. However, the information about disinfecting a cage would apply to cleaning a cage after a bird has been ill, reusing an old cage for a new bird, or any other reason for that matter.
Disinfecting Cages
by Annieokie
If they do have mites, they came with the birds in that cage. So the cage will have to be cleaned. But first you must be sure that's what is causing the itching. Sometimes, not always, a mite infested bird will have little ragged places on feathers. It's not too common to be able to see the mites because they usually hide in crevices and cracks of the cage and perches except at night. Derbyan's suggestion about using a white sheet is well known but you still have to get the medication so why not take them to the vet and save some time?
Have you done a super cleaning of the cage? The birds will have to be put elsewhere for an hour or so while this is done.
Plan ahead for this because you may need to buy a few things to be ready, like new perches and new food.
If you have a bathroom vent fan, turn it on and keep the door closed so the birds aren't hurt by bleach fumes. You need to get out after each step, too.
Remove all toys, bowls and perches. If the cage is small enough, take it to the bathroom shower or tub, wash it down with diluted dishwashing liquid, scrub every little nook and cranny and underneath with a brush and rinse really well. Then spray it or mop on a bleach solution, 1 part bleach to 10 parts hot water. Leave it for 10 minutes. Go back and spray it again, leave it for another 10 minutes, then do this one more time. The goal is to have the wet bleach solution on the cage for a minimum of 20 minutes. Then rinse and rinse and rinse. A shower spray is good to get all of it off. No trace of bleach can be left on the cage. It's toxic, plus it will rust the cage if left on it. Dry the cage well before returning the birds to it.
Throw away the perches if they are wood because mites are so tiny they can hide in the crevices of the perch. Also toss any fabric or rope toys. You can clean plastic and acrylic toys with the soap and bleach, rinse them and dry them well. Toss any food that was in or has been stored near the cage. Wipe up around the cage with damp cloths and throw them away. Do walls, baseboards, floor and tables nearby.
Above all, DO NOT spray any insecticide in the room with your birds unless you can take them away before spraying and keep them away for several days.
Gee, that sounds like I am on a lecture circuit. 
I just don't want a misunderstanding that could harm the birds.
I just don't want a misunderstanding that could harm the birds.Annie