Those beggars are very often running scams when they say "Lost Job, Please Help." There are many reasons to NOT support them.
The short answer is no. The long answer is: Yes, but only if you work for an organization that can ensure the money is spent wisely.
www.theatlantic.com
www.homelesshub.ca
David Barnett asks whether it is ethical to give money to street beggars. Will they only spend it on booze as the cliché suggests – and if so should that even matter?
www.independent.co.uk
The consensus I found when scanning several articles is "qualified NO." The qualification is "don't give them anything directly. Instead, donate to a a homeless shelter or charity specializing the aiding the homeless." Further discussion is that when you donate to a person directly, that person has no way to multiply the value of the dollars you give whereas a charity can do bulk food or clothing purchases at a discount and can then serve more people.
Just for the record, my wife and I support a local food-based charity that claims that with the power of bulk purchases, they can take a $1.00 donation and turn it into $15.50 equivalent retail purchases using the power of bulk/wholesale purchases (and also by omitting one or more layers of middlemen.) My wife investigated those folks and they are legit. In south Louisiana, we support Second Harvest. Can't speak to any other regional food bank system, but this one is pretty good, low overhead, and food is targeted to needy families and individuals. I'm guessing we add between 5% and 8% of our food purchases to feed others. (It varies depending in where we shop.)