I detest canvassing, but respect it can be effective in some situations. The challenge in canvassing programs is your need to attract and then manage the type of salesperson who is not afraid to knock on strangers’ doors. This type of behaviour is against most of our gut instincts (except on October 31 if you are a kid, of course!) But some enjoy it, and are good at it, and if you have that mix, and the ability to manage and oversee things, you an find business.
See this thread on Contractortalk.com for some really useful insights.