Recently bought a couple of Kong toys because they come so highly recommended. One's the traditional kind that looks like a buttplug and the other is a bone shape with big ridges in it. I filled them with peanut butter and put both in the freezer. They went down a storm when I presented them to our pup later. However, I cannot get them properly clean now, despite two goes in the dishwasher and a long soak in hot soapy water in the sink. I can't reach the deepest nooks (and neither could he with his little tongue), and I cannot get the clumps of food out. Does anyone have any useful remedies? It was suggested they could be used in this way so I'm kind of surprised I can't get them clean. Maybe the peanut butter is made from extremely staunch peanuts.