What you said about cross training the detection dogs makes a lot of sense.
I once watched a demonstration at our volunteer fire department's fire prevention fair of a service dog used in arson investigations. He was trained to detect the presence of accelerants. It was amazing that he could detect the burned substance which was started using gas, lighter fluid, or other common chemicals.
The method of alerting on each one was the same, so I can see how he might get confused if someone tried to train him to alert different ways for different substances.
The dog was also versed in the "stop, drop, and roll" which really impressed the children at the fair!
