Every year, in the last week of January, volunteers from and partnering with the Departments of Veterans Affairs and Housing and Urban Development go out and take a census of America's homeless population (called the Point in Time count). read more
As for why non-veteran homeless people might pretend to be veterans, well, if they can expect to get some extra sympathy/resources/money by pretending to be a veteran, there's not exactly a major risk for them to do so. read more
For starters, not everyone that says they are a vet is a vet. Many so called homeless are not, they're panhandlers. Many veterans are also doing fine and not homeless. There are however legitimate homeless folks who are veterans. Some of those are simply former military and not veterans. Of those, a fraction are actual veterans. read more