I have however, given food to one really old dude that looked like he needed it. He thanked me vigorously.
There is a difference between being homeless and panhandling. Most people who listen to the Charlie Hodge Halftime Show would agree
Basically, if they are on the corner at your nearest intersection, they are panhandling (which is illegal in downtown Austin, IIRC). If they are downtown on 6th, beggin for money from drunks, they are probably homeless - The ARCH is nearby.