BUT... IT LOOKED GOOD ON THE HANGER!

Today has been spent shoes shopping, and I had the most fantastic face day imaginable. Unfortunately, my outfit choice added about fifty pounds and left a great deal to be desired. I bought this dress online last year, and it looked absolutely perfect on the model. When I tried it on, I went "ICK!" and promptly forgot about it until this morning. 
I got dressed in a rush, and didn't realize how unfortunate I looked until my mum asked me if I forgot to do laundry again (I have been known to put together some highly unfortunate outfits when I'm too lazy to wash my clothes. It happens about once per semester, and I usually meet everyone I have been avoiding on that day.) I really need to invest in a full length mirror! 
Why is it that on the days you look absolutely gorgeous, you don't really run into anyone that you have been avoiding, but on the days you look kinda crappy, you see EVERYONE and they look ten thousand times better than you ever have?