Urine and what kind of seasoning? Without further information, my first suggestion would be to check for homeless, they often use back corners as urinals. Mothballs and bright lights may help to scare them away. Afterwards, try pulling the stove away from the wall and scrubbing eveything with liquid bleach. Be sure to use the liquid bleach, the solid stuff in ineffective.
I know that this response is a little late but judging from the proposed solutions you are still looking for an answer.
First, you really need to run the dryer vent outside ASAP. I have rehabbed houses where the tennant was using the dryer to help heat the house and the in just one winter the utility room and kitchen walls and ceiling were covered with mold spots.
Second, the odor you are smelling are probably mercaptin gas which is produced by a wide variety of products including urine from cats, dogs, mice, roaches, people, raccoons and most other animals. It is also produced by rotting meat and vegetable matter but is smells different because the exact molecular construction can be quite different. One of the things you might consider is when the humidity gets above 50% urine residue starts producing odor. The enzyme products available over the counter must be kept wet for a long period of time and will not work at all if the area with the odor has been washed with detergent. It kills the bacteria. There is a product called OdorXit.com that does work and is permanent.
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