Cleaning any piece that has cold paint on it is subject to debate. most people prefer to leave the piece as found which now I agree with most of the time due to some bad experiences using a dishwasher. My wife likes to clean everything I bring in and unless I am there to stop her the piece will end up in the dishwasher. This works for a lot pottery but not cold paint as shown by the two photographs I have included in this section.

If you have a piece of pottery with cold paint find out the type of glaze it has on it and if it is either chalk or pottery. A lot of older pieces were made of chalk and painted with cold paint. If the piece is high gloss glaze then any cleaning you do can damage the piece. My advice is to wipe it off with a damp cloth with no detergent and leave it alone unless there is a large build up of grease of the piece. Then you can take a change and find a spot not visible and use a mixture of water and a light detergent like Dawn, using only a small amount of detergent.  Rub gently to determine if the cold paint is going to stay on the piece of pottery. If not stop and enjoy the piece the way it is.

Cold paint on chalk pieces adhered to the material better when it was applied and can be cleaned easier than pottery with a high gloss glaze. But again start off with a small test area to insure you can clean the piece.

BLEACH, this covers all types of pottery and toys DON'T use it PERIOD.

The same goes for older toys, but generally the  toys can be cleaned since they were painted over metal with has better adhesive characteristics than pottery. First determine if the toy has paint that is lifting from the metal if so don't try to clean that area. Again as in the pottery do a cleaning with a damp cloth first and work from that point with a mild solution of detergent and water.