Cat pees on my dogs' beds, why?

For the last few months, I've come across the odor of cat pee every so often. Fortunately (unfortunately for the dogs), its mostly been on the dogs' beds we have throughout the house. The cat was nice enough to pee once in my laundry basket however, after I put in some of my workout clothes to wash. My wife has a bit of an affliction for cats, we have 4 total along with 2 dogs. We've rescued 2 of the 4 since moving into our house 5 years ago. Our pee bandit is one of the original two. My guess is that he might be unhappy with the latest roomate we found in our front yard this winter, but that doesnt explain why he goes after the dogs' beds. Its testing my patience and I need to figure out a way to curb this new habit.