I'm Lucy, and I'd be happy to answer your questions today. I'm sorry to hear about your situation.
Honestly, the best way for you to verify the smell may be to bring in a friend who's a non-smoker. They'll be more sensitive to it than you are. Smell is tough to prove in court unless you have a furnished apartment where she can bring in something like sofa cushions. However, the landlord can bring in a small portion of the rug, if it needs to be replaced due to the smell, and the judge can smell it. The landlord can testify as to the smell, have third parties who've visited the property testify to the smell, and she can bring in cleaning bills that say cleaning was done to remove an order.
At the end of the day, she just needs to prove that, more likely than not, you caused a smell in the apartment that needed to be removed. If you admit to smoking in the property and to not having a deep cleaning done before you left, that's actually going to help her case. So it would help if you had someone else who could testify that the apartment doesn't smell.
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