Shadow hasn't been out with us much due to his surgery and age, but he doesn't care about caches, he wants to find the girl dog who left that pretty scent before us.
The wolfdogs seem semi interested, but not enough to tell us where the cache is. Tok found a few, he stuck his nose in a hole and figured it wasn't for him, and walked away. He never thought to say "hey guys, this one's for you."
Tok has been to every cache with us, and the most interesting thing he can find to do while we're sitting around logging our find is to pee on a tree, or two, or ten.
Tikanni thinks everything is for her, including the log books, pens, Tok's tail, our trekking poles, and my feet. But as far as a big metal box or plastic container, she doesn't seem to care much. She's only been on 3 caches with us thus far, so she may catch on more.
It's tough to get them to sniff and find since they can't ever be off-leash. I'm thinking something more eager to work with you and much younger to start, like a golden puppy, lab, or shephard, even a well-train border collie may work out very well as pro-cachers if you cache with them as often as you can.