Racing boy bragging claims aside, anyone who has been driving for man years without causing a serious accident is a good driver in my book. Don’t let the rhetoric barfed out by the anti-car folk in here and elsewhere make you think otherwise. If you are operating a bulky machine regularly under a variety of circumstances, making the occasional mistake or causing the odd minor damage to the bodywork is inevitable for most.
If you have spent your motoring life so far driving without having been involved in serious incidents that were your fault, and have not had serious near misses due to genuine incompetence or lack of skills, you are a good driver, or good enough, end of.