When you are upset that you put on real clothes today, and the only person who will see you in them is your husband, and he isn't coming home till bedtime, which is when it's totally acceptable to [still] be in pajamas.
When you know your dog's napping patterns so well that you can predict the exact time in the afternoon when he'll have one of those dreams that makes him softly bark and flinch his paws in a way that means he's totally chasing something in his dream. So you can try to catch it on video. (It's so cute it could go viral for SURE.)
When the only time you left the house in days was to go to the drugstore around the corner because you were out of wine.
When you have left voicemails for people for an hour without actually speaking to anyone, so you open facebook just to remember that you know real people who do stuff outside their house.
When you stick a post-it note over the webcam on your laptop because it's 11 a.m. and you haven't showered and you are in a Napoleon Dynamite t-shirt while on a conference call with colleagues, and there's no way you want that camera to accidentally activate and show people what you look like.
That's when you know you are getting a little too comfortable working from home.
But it's AWESOME.