Because your senses are heightened and you see and smell better. You find things that weren't there when you weren't hungry. Spidey hunger sense.
Ha ha i was thinkin that same thing yesterday.... I look in there like, Why cant there be something to eat? or, I dont wanna make that!
because each time you go back you get closer and closer to eating the 3 week old leftovers that you should have thrown out 2.5 weeks ago. and then you cave in and eat it hoping the microwave will kill any bacteria, germs, etc. that have had almost a month to grow and prosper.
I do because i think i can make something out of nothing so i keep looking for nothing..wait does that make sense..im on a sugar high!