I worked for a brand & marketing company for 15 years and I observed that most of my clients had pretty short memories when it came to how they felt about me. If the last few milestones were really great they quickly forgot an incident. Obviously, the more impactful an incident, the longer/more positive milestones had to be. An incident too impactful got your fired - but, in general, this was my experience.

Even in their recent history Microsoft has repeated incidents, but also has some very big positive milestones. Also, keeping in mind, some customers will only see the positive milestones.