Cleanliness is a low priority
Any office manager will happily tell you to clean up your damn cubicle, but when you work at home your office manager is a lot more forgiving. And good looking. Because it's you. Dishes pile up, the discarded remains from taste-tests crowd your counters, and, before you know it, you're using your girlfriend's March issue of Vogue as a plate.
Desperation-fueled mid-day grocery store runs
Avoiding rush hour shopping as a perk, but if you're going grocery shopping during the day, you're probably just making the excuse that you can eat an affordable lunch there. Instead, you buy a bunch of vegetables that eventually go bad and seven Lean Cuisines that you finish two days later.
You eat at unreasonable hours
Although it's easy to scarf down the official breakfast of a lazy person trying to be healthy (banana + a cup of water), it's likely that your morning meal doesn't come before noon. And if you're going out to lunch, you've gotta race to make it before the restaurant closes to prepare for dinner service, and pray they're pretty lax about people eating pantless.