You can make just about anything fly, but if something can be fixed, It is better fixed. Discerning airworthiness of an airframe has little to do with the question "Will it fly?", and everything to do with the question "Will it fly well?". An airplane that does not fly well is an issue of safety. When I built my trainer, I made plenty of mistakes. The gentleman that trained me would meet with me every week and inspect the progress I had made on the kit. If something was not right, he would tell me why it was not right and suggest a fix. Everything right down to the final preflight before maiden, he used the opportunity to teach me good building habits and to pass along good practical information. In the end it all comes down to safety... Not just the safety of bystanders, but safety for the airplane itself. Giving it the best chance of a long, successful life in service. It is far better to pass on a model, or retire it to become a relic in the rafters than to loose it due to poor set-up and construction. And if an airplane does not fly well, then IMHO it should not be flown at all.