I got 4 crazy ass dogs, and had 2 since puppies. And the 2 we had as puppies have eaten full bags of Hershey's kisses, paper, stuffed toy stuffing, rotten chicken wing and ribs bones from the trash, tennis balls, shoes, twigs, showlaces, 1/2 of 2 remote controles, including 1 battery, and an assortment of other stuff they found. they made it ok. The only thing they have ever had a problem with was not the greenies we gave them, but the damn rawhide bones. One of my dogs chokes on them once a year, but she will just hack it up and be fine with it.
As with any treats, you just gotta be careful with them, and be there when they are eating them.