Having the fortitude to say "sorry all we just can't go" is an essential way to reduce the risk of a disaster. I have been an inexperienced boggy as well and think this is a paradigm which needs to be part of the EMS culture in training and practice. Maybe this is something which can be taught and learned, maybe not.
Managers and clients with the fortitude to say "Thanks Skipper, we understand and support that decision" would be the other half of that equation.
Interhospital transfers in the middle of the night where the helo is used so the ground crews don't get woken or taken out of their response areas are a couple of examples of a bad mind set exhibited by many dispatchers.
Things which "could" stop a flight for me would be:
A/C unserviceabilities
Wx/genrally
Wx/Lack of alternates
Wx/icing
lighting
destination hls
navaids
lighting
notams
Whole crew skills/competence
Any of those can be evidenced debriefed and discussed later in the cold light of day.
FWIW
DD