Could be a simple case of poor ventilation. If you cook a lot then it's gonna be layered up on everything.
Years ago in a house with 3 room-mates we tried to diagnose a mystery stench right before a huge party. One of my friends discovered a gigantic rat dead in a trap between the fridge and stove way back under a prep table. It was completely flat. Big maggots had hollowed it out. Nose to tail the thing was easily 24". I had set the trap while drunk and forgot about it...
Once that was out of the house smell- gone! And drank 5 gallons of 20% mead. WooHoo. Beer...
Don't you mean WooHoo mead?
How long before had you set the rat trap?
We used to have a mouse problem in my garage. A couple of summers ago I came home from vacation to find a bunch of really fat dead flies in a carboy full of starsan and a couple of flat mice in traps that I had left set. Bad smell too. Then there was the one that fell out of a jacket I had left in the garage . . .
It wasn't until we got a new furnace with a lightly smaller footprint that I was able to find out where the mice were coming in and seal up the gaps. No problems since. Well, there was something eating the peanut butter out of the traps for a while, but I eventually caught it - a shrew, it took a lot longer to catch because it was so much lighter than a mouse. Anyway, no problems since then.