If anyone ever asks you to dog-sit for them, the most important thing I think you can ask if you will need to leave that dog while you're at work is "Does your dog have any separation anxiety?" Because if you don't, and you leave them, there is a simple equation.
It also equals one highly annoyed wife who had to miss the Doobie Brothers concert because she could no longer trust the dog alone in her house. It equals my right to say "I told you so" until the cows come home (and I don't think the cows are coming home until the first frost). In the variation of the equation where the moody wife is also pregnant, it also equals one husband who's sleeping with the dogs tonight.