"No. I will solve your problem for you. And you will pay me. And you don’t have to use the solution. If you want options, go talk to other people. But I’ll solve your problem for you the best way I know how. And you use it or not. That’s up to you.
You’re the client. But you pay me." - Paul Rand, 1993
Personally, as an aspiring full-time Graphic Designer I'm 50/50 on the subject. Sometimes working for free with a client can lead to bigger things, but the idea of working for free undermines your work, spec work is an example of working for free as spec work is essentially showing potential future employers and companies samples of your skills, there is a limit to spec work, if the client is expecting you to go above and beyond in your work without pay then its probably ideal to drop out of the opportunity. Unpaid work can also benefit your resume and portfolio, whether you choose to consider and unpaid internship or simply support charitable organizations this can benefit you in the long-run, if you chose the route of an internship then you have access to a network of Graphic Design companies that may take you on after your internship ends, and the gain of knowledge whilst working around other designers.