I would be concerned with selling it - if the contractor did bad I would feel responsible, almost liable. If I gave it away it was done in an effort to help the consumer and even though I referred it out, I think any animosity from the consumer with a bad experience would land on the contractor.
I share your concern. Therefore I am careful who I sell for.
I have a seperate business that handles sales for several other contractors. Before I sell for them, I go through a "hiring" process. I then do on going training. In a sense, they are no different from subs or employees. I've "fired" a number of them because they didn't meet my standards.
I get a lot of leads that aren't a good fit for my company. Rather than simply burn the lead, I try to make something positive of it. I've sold a lot of jobs within a mile of my office for other contractors. A few neighborhoods simply can't afford my price. Sometimes they need it done yesterday and I'm booked for a month. Sometimes it's a job I just don't want my regulars doing.
When the contractor screws up, I hold his feet to the fire. I'm an advocate for the home owner. I've yet to have a problem with a contractor not fixing a problem. I guess they don't want the customer and me
on their back. The customer might give up, but I won't. And the contractors I sell for know it.
It really comes down to how we define our business. If we are a painting contractor, then our job essentially is to put paint on the wall. I view my business as a sales and marketing company. My job is to generate leads and sell paint jobs.
How we define our business ultimately determines where we focus our efforts and how we address these issues. How we define our business ultimately determines what kind of business we have.