A man in Japan was recently accused of attempted murder by introducing a caustic material, hydrofluoric acid, into the shoes of a female colleague he was stalking. This story was covered, among other places, by France 24, a coincidence since in Paris in the turn of the last century, death from poisoned shoes wasn't apparently uncommon after blacking them with aniline dyes. Courtesy of the terrific site Invisible Paris and a paper from 1902:
Jean (H)Elias, a nineteen-year-old shopworker, had recently given a worn pair of yellow shoes to his local cobbler for a clean up and to have them tinted black. Unbeknownst to him, the cobbler had used a substance called aniline for the job – a 'poison dangereux' writes Le Petit Parisien, whilst also noting that it has pointed out this fact 'à maintes reprises' (many times).
Apparently, aniline (still used in polishes today) has a characteristic fishy odor, and hydrofluoric acid has a pungent, irritating odor. So look out, because smelly shoes can kill you!