These are great for kibble and other food that tend to roll off flat plates. In a pinch, aluminum foil formed into a small bowl can also work. Canned and other moist foods can leave a residue in the bowl. Especially in the warmth of summer, bacteria can grow quickly leaving smells throughout the house and attracting flies if left out in the backyard. Many dogs will lick their bowls clean leaving a very thick saliva residue that can be difficult to clean off.
Cats are likely to eat a bit and then leave bits and pieces lying around.
They pick at their food, taking unappetizing pieces out of their bowls and dropping them wherever. The bad part of disposable dishes is that they can feel wasteful and the ugly part is thinking about overflowing landfills. However, they can be a useful temporary solution and if you shop around a bit, they can be had for less than 10 cents each. You should always try paper dishes before you leave. Some dogs may eat the plates in which case they have to be disposed of before he ingests them.