The idea of a "good bike' is an n-dimensional hyperspace, where n is a large, possibly infinite, number.
There are so many criteria, which differ from person to person and, form time to time and situation to situation within one person that it is like a Platonic ideal, something to aspire to, while realizing you will never attain it.
All that being said, the times I find myself telling my bike it is a good bike are times it has taken care of me; handled dicey terrain with out incident, carried me farther than I thought I could go that day, felt faster, or more comfortable than I expected, just, in general improved the ride experience.