I've been thinking about forming a co-op for a trusted network of freelancers, to handle the crummy parts of the job (sourcing, selling, collecting) while encouraging the good parts (building, branding, partnering with quality colleagues). I had similar experiences being left with fake jobs/bad credit through freelance markets.
Thanks for sharing! I generally take longer-term gigs, so consistent dealflow isn't as big an of an issue for me. OP, what are you planning to do to fix your offline-network problem?