You may be right, doorknob. I imagine that if a person whose drug-of-choice is IV heroin were to shoot up a few syringes of water just for kicks, it would set off an avalanche of cravings.
I've known people to do that, just to get the rush from the ritual around the using process.
Personally, if I see a snake and am not sure whether it's poisonous or not, I'm not picking it up. The risks outweigh any potential gains.