Mariner, an interesting question, and one which probably depends on the incentive/motive driving someone in this career direction.
For example, I would doubt that those people who tend to "rubber-neck" at a motorway accident, would be suitable.
I remember attending a lecture at school from a member of the AAIB(name forgotten), and it was riveting. This guy just thrived on the challenge of discovering the cause of an accident, particularly where this proved not to be straightforward. He detailed how even simple pieces of forensic evidence could be interpreted - examination of a light bulb filament could indicate whether it was on or off at the time of the incident.
Satellite TV often repeats the Copa Airlines 737 Panama crash investigation, in which Tom Haueter is very thorough in his brief, and frustrated by following the "wrong" lead, at one point.
I guess the "interesting" aspect is more than balanced by the "boring", but it is certainly an occupation that I wish I had explored more thoroughly.