I won't say it can't work. I am saying things she be done in a manner that puts the odds in ones favor. Your excellent bitch can be a starting point, even if she is not from a super-duper family of dogs. It will take more time and the end game will be further down the road but it is possible. Your good bitch to another complete package dog related to her, keep the good ones and go from there. In time, 4-6 generations later there will be solid family to draw from. That is an over simplification and tons of time/work involved. Every good family had to start somewhere and knowing that every dog does not have a pedigree with 100% success rates top to bottom. So with your excellent bitch as a starting point you can go forward. My plan would be to breed her to something that is not only a solid dog but from a family of solid dogs. If you are 1 for 7 in that litter then I would find another bitch.
The jist of successful breeding is putting the odds in ones favor. Sometimes it may be out of the norm, it may involve a cold dog, and sometimes even untested dogs. The key is to have an end goal in mind and be honest with the results and go from there. EWO