NO more SPEC work!

I came across No ! Spec yesterday, after talking about some of my recent client troubles at work. In the graphic design industry it seems pretty common that people will try to get you to do work for them without paying you. Speculative work would be a scenario where if you do this one thing, they'll pay you for the next thing. There is no contract or guarantee that more work or payment will come at all. Contests are also this way, in that it cheapens professional designers by having people spend their valuable time working on something with no compensation. As a professional designer, I can potentially be spending my time working on paid client work, or improving my portfolio. By wasting time on jobs with no benefits, it really serves no purpose from my standpoint.
The past few potential gigs I've lost due to artists who will lowball their rates to a ridiculous proportion. I don't think my rates are high at all, and I make them up based on the client, but it seems like clients themselves aren't willing to spend money for quality. I recently got in contact with someone who had wanted me to do an illustration for a t-shirt. We had a few back and forth e-mails, and then he told me that he had no budget to pay me but would give me free shirts and promised more work in the future. This job was also advertised on Craigslist as a "job," if it was advertised as "do stuff for me for free" I doubt anybody would have responded to it.
Clients: If you want quality work done, you're going to have to pay proportionally for it.
Designers: Don't sell yourself short, you cheapen all of us by bowing to the whim of these people. Clients should have to sell themselves to you just as much as you have to sell yourself to them.