Why make a bed when you're just going to mess it back up again the next night. Same logic for dishwashing. All that's on your dishes is food, most of which you've already put in your mouth. There's nothing 'dirty' about 'dirty dishes', it's food. However your food smeared dishes will get 'dirty' if you leave them out for too long and let bacteria etc start living on it. Although this has never been a problem in my experience (either I have a strong immune system or my microwave does good sterylization), my habit of reusing unwashed dishes has aesthetically offended some of my past roomates. To solve that problem I just hid them from view.
However, I recently realized a way to make this habit more acceptable for use by the general public (at least those that follow logic).
Put your 'dirty' dishes in an environment in which bacteria do not grow (at least definately not fast enough to become a problem between daily microwave sterilizations) and in which your dishes will not be seen much. This environment already exists in your home, it's called a freezer. If you eat a lot of frozen food you wouldn't even have to worry about the energy wastage of opening the freezer since you'd be removing food at the same time. I'm not sure what that energy wastage figure is, it might make this into an overall un-environmentally friendly idea, but I don't think so (depends on how many times a day to remove the plates).
According to www.H2Ouse.org dishwashing makes up 1.4% of total USA national water use (daily per capita = 1 gallon). So this habit will not save as much water as my toilet water conservation instructable but it will still save a lot of water.
SUMMARY: instead of washing your dishes, just put them in the freezer to
A) prevent bacterial growth and
B) keep them out of site.
By re-using them without washing you save water and more efficiently consume food (as remnants of previous meals become incorporated into following meals)
Step 1: Do It
then get up,
walk over to your freezer,
then have your brain send the appropriate signals to your arms to open the freezer.