It is encouraged by the FAA that the airman provide the AME with a copy of his 8500-8 (the medical questionnaire) prior to the AME officially downloading his application. That way, if something turns up that would otherwise necessitate deferral, it can be dealt with in advance of an "official examination", and save everyone a lot of paperwork and heartache.
Airmen self-certify every time they get in the cockpit. The vast majority of AMEs over here are doing their best to work with the airman to help him continue to do that safely.