I actually turn down paid work for volunteer work. Many times I don't even think twice about turning down the paid work. For me personally it is all about who would I rather have in my box of connections. Would I rather have a production company who clearly doesn't know what they are doing, slapped the production together, and probably won't last pay me $450 for the day? Or would I rather work for free on a shoot for people who are very honest and very professional, who have spent the past 4 months doing pre-production to get ready for that shoot? For me the choice will be the same every time. Why? Simple. While I may not get paid for that one day of work in the long run those guys I help out are going to get better paying gigs because their product and attitudes are in line with who more clients want to work with, then the production crew who simply says yes to everything and throws a piece of junk together at the last minute.
This is something I learned early in my career. And it has bled over to my work. There was a question at the beginning of this asking how many times crews have bailed for a production. For me, I have never had a single crew member bail on me for a free shoot. Why has no one bailed? Because when I go into my productions I make sure that not only I have the highest level of professionalism going in but everyone around me has the same attitude and drive. I take the time to plan everything out and I go through everything with the crew. Lay it all out. Be completely honest. This has worked for me for years. One of my first lessons I learned on a set was "If you want to be treated like a professional then you need to act like a professional."
*Steps down off his soap box*