Or if I sprayed the seats in the airports lounge or restaurant, the bomb-sniffing dogs would become butt-sniffing dogs, to the major embarrassment of security. This last, while humorous, would go a long way toward discrediting the security force.

Chemicals that aren't detected themselves but undergo slow change (oxidation, hydrolysis...) to the ones that trigger the detectors (including but not limited to the dogs) bear a lot of potential too. I remmember an incident in a friend's school couple years ago, with some crystalline stuff that hydrolyzed to (I think ethyl-) mercaptan. A bottle of a detergent the janitors use for floor cleaning could be contaminated with something similar as well. Imagine the puzzled dogs the next days. Those cute little ones occassionally used for sniffing drugs could look especially funny.