Alas, we've already had our entire unit heat treated once and sprayed twice. The exterminator that did it offers a 6 month "guarantee" so the subsequent callbacks have been free but he hasn't exactly been confidence inspiring to deal with.
Our lease has a clause where the tenant is responsible for paying for treatment. And the guy they called out was more than a month's rent. So I wouldn't be too surprised if someone else in the building had them and was staying mum about it.