关于从apartment搬出，apartment要扣不合理费用怎么办？

I am moving out of an apartment. The apartment says there is odor in it and is going to hire a contractor to remove it and send us the bill which would be about $500. However, I moved out a few days already and cleaned it up very well, and I do not smell any odor in the apartment. I think the apartment's opinion is not objective and felt being blackmailed. What can I do?

十分谢谢！