Can anyone confirm this? For those unfamiliar with the term "bath salts", he's not talking about actual bath salts; it's a street-name for a recently common local drug, also known as monkey dust.
If it's true (which I doubt), then it would be the first recorded instance of it happening, as far as I know.
Nobody has ever legitimately reported evidence of folks handing out poisoned/drugged candy on Halloween. Ever. There are three things that were close to it, but none of them lived up to the rumor.
1) Crazy parents didn't want their kid to go trick or treating, so while the kid was out, they laced Pixie Stix with rat-poison or Comet or something. When the kid returned, they mixed in the toxic candies in with the actual ones on the sly, and then claimed the kid must have gotten them from some crazy down the road (when it was actually the crazies in the house).
2) Kid with his uncle on Halloween. Kid got into the uncle's heroin (or something like that) stash. Uncle didn't want to get busted, so he tried to make it look like the kid had picked up heroin-laced Snickers while trick or treating.
3) Woman got sick and tired of stupid drunk college kids doing half-assed trick or treating, so she had a standard bowl of candy for the little kids, and a bowl of junk for the college kids. The junk included things like corks, mousetraps, etc... and those ant-traps things that are basically toxic wax in a Carmex-sized container (that you can't get into without tin snips and blatantly say RAID ANT-BAIT or suchlike on them, with pictures of cartoon dead ants). She was busted for handing out poison, on a technicality. (PS: This woman is my hero. Nothing against college kids, but I like the idea of junk treats for annoying folks)