It can be anything that's safe for dogs to eat. I'm talking good stuff. Human food included. Sugary cereals allowed. Children's snacks allowed. What makes your dogs absolutely crazy? The only requirement is that it is relatively non-messy (no need to wash hands after touching, so nothing like cheese, cooked chicken, etc).
Our 7-year-old rescue has been with us 3 months and it's clear he has some serious social issues with men. He is STILL afraid of DH and it's gotten to where he runs and shakes and sometimes even barks when he even hears DH coming. I do not want it to get any worse than it already is (it's bad) so we are embarking on a serious counter-conditioning plan. If it doesn't improve within a month or so, then I am going to have to call in a professional. DH needs to carry this extra special non messy extremely high value bag of treats with him everywhere, and toss the dog one whenever he is nearby.
It has to be REALLY high value because on top of our dog's social issues, he is not a food motivated dog. Sigh. Right now DH has pieces of human beef jerky from Costco but it's a little messy on the hands. And I mean beef jerky for humans, not human jerky.
Poor dog. And poor DH, who is taking it pretty personally that the dog doesn't like him, and it's stressing me and the kids out as well because DH takes it personally (which I believe contributes to a vicious cycle of "OK, if you don't like me then I don't like you" which makes the dog fear him even more because I'm certain the dog can sense the dislike. He is an EXTREMELY SENSITIVE dog).