Blockbusters often don't sweat the small details and frankly, most movie-goers will never notice the odd continuity error, anachronism or similar stuff-up, especially on first viewing. That doesn't mean we can't ponder the real-world problems that would plague fictional cities, governments and in this case, the humble corpse salesman, post alien invasion.
This three-minute clip from Dorkly poses the question: What happened to all the dead Chitauri soldiers at the end of The Avengers? Unlike video games, vanquished Hollywood foes don't magically vanish after a time -- no, some (admittedly non-existent) person would have had to grab a mop and bucket and get cleaning.
Or, if you're more enterprising, you could round up all the decaying bits and pieces and attempt to flog them. That's what poor Bargain Bill here decided to do and well, it hasn't quite worked out for him. At least he's offering to throw in 10 feet for kids over 10. That's hard deal to pass up.