Hoarders do not notice the messes and smells (my former neighbor was a lovely lady, but she just had to be removed from her house and it was condemned ..it took a professional crew to get it inhabitable again) so having someone talk to her is not going to work. The company is going to have to step in and take drastic measures to get it cleaned up. I would talk to your supervisor, either by yourself, or as a group if others are complaining, and explain the health hazard that it is. There is probably a copious amount of mold growing in there which is extremely bad for breathing. If that doesn't work, keep going up the chain of command. Again, telling her to do it herself will not work. I bet her house is just the same, thus the fact that she smells too.