After a few months of living with flies, the dust canister of your vacuum cleaner is coated in dark gray goo. When you empty it, you have to find something to scrape the fly guts off the inside. There is a distinctive smell that is slightly sweet and more-than-slightly nauseating. You count the fly bodies, as if knowing the number of carcasses you vacuum will convince someone that it really is as bad as you say it is. Fifty-seven in the bathtub, thirteen on the counter, but when you try to count the pile in front of the sliding glass door, you lose track somewhere past fifty.