In all fairness, I think charging for services depends on the situation. I'm a pretty good carpenter, and able to tackle everything from interior design and layout through framing, rough-in electric, plumbing, insulation (including specialized sound-baffling for home theaters), sheetrock and trim. Installed a bar and a few cabinets as well. But if a friend needs a hand, and I have time, I help out as much as possible.
The key difference is that I no longer do contracting for a living. If I did, and side jobs became like a busman's holiday, I probably would steer clear of them as much as possible.