What is the psychological term for someone who is aroused by the smell of urine, garbage or decomposition?
There is a woman in my building who reeks of stale urine and doesn’t seem to be bothered by the fact that everyone else can smell it. Her apartment also smells of urine and garbage constantly. Other than this, she seems to be an intelligent and kind person. I’m sure it must be a psychological condition and has a name.
Where is the sexual link here? 
Quite. I see no evidence that she even likes it. Perhaps she just has a poor sense of smell.
There are physical ailments that cause an ammonia body odor. There isn’t much that can be done about it. As far as her home smelling bad, she may not have the energy to clean if she has a chronic illness.
Alternately, she may be a hoarder and/or clinically depressed, and has just become numbed to the smell of her apartment and belongings. If the place is a mess, she’s probably let maintenance go since she doesn’t want anyone to come in to fix a broken toilet, etc.
Being sexually aroused by excrement is coprophila or scatophilia. This seems more likely to be a person who by virtue of constant exposure no longer senses a stimulus. This is sometimes called sensory tachyphylaxis or habituation. Perhaps, as suggested, depressed, perhaps just chronically incontinent and thus always exposed and unable to sense it. My then girlfriend, now wife, had a roommate in grad school who always wore tea rose perfume … always. And since she always wore it she could no longer smell it so kept putting more and more on. We knew she was coming from a block away.
I live in a large complex and somebody brought in bed bugs, so we are routinely inspected every 3 months. They tell us not to use disinfectant cleansers for 48 hrs. before an inspection because the dogs can’t do their job sniffing out bugs if there are strong smells. She is fined $50 because they have to do her apartment visually.
She is not disabled so there is no reason she can’t shower and do her laundry. Also, we all take our trash to a chute at the end of the hall every morning. She goes downstairs to sit in the lobby every day and passes the trash room on her way so she could easily dispose of it.
I would think she has some kind of mental problem or gets some thrill out of this to be willing to pay $200 a year. She has lived here 5 yrs. now and the fact that she isn’t evicted makes me think that she has gotten a doctor’s note for the landlord.
Not sure what business it is of yours to begin with, and I’m more than a little distrubed by the fact that you went straight to “sexual fetish” while bypassing a million other plausible answers.