Project end blooms

All projects have end climax tensions --about acceptance of client or final test faults--
everytime during final test we find lots of problems-
managers are grim after the the last day announcement0
How to handle the client specific rejections -how to show the project as successful deliverable?--
almost all projects can be made 90% perfect --for making the extra 5% correctness people do lot of things-
You need to deploy specilized skillset to achieve 99%