Can a jar that has had botulinum food in it be cleaned
Typically if you suspect that a jar is actually contaminated with botulism the procedure is to leave it sealed and throw it away. This is due to the ability of botulism to become airborne.

(see: http://nchfp.uga.edu/how/general/identify_handle_spoiled_canned_food.html ) 

The washing of old gross jars is usually aimed at high-acid foods that may have popped the seal and become mouldy, stinky, or just plain old.