Oh, well over 20% could use the buck or two. It's just that 95% of them won't put it toward good use. I work with the sort of population that does a lot of panhandling. I recognize a lot of the ones that I see in my area and I know exactly what they spend extra money on, a lot of it worse than booze.
I tell people to never give panhandlers money because 95% of the time it doesn't help them at all. They turn around and buy something that'll just harm them. Stuff like bottled water (I keep a pack of cheap bottled water in my car just for this purpose) and food (perishable or single-serving/not for individual sale stuff they can't sell to corner stores) are the things I recommend giving. If you have time, the ones that are actually hungry will always appreciate a sandwich or fast food or pizza and will always take you up on the offer.