I tend to stick with any professional (vet, farrier etc) that is able to say the words "I don't know". At least then I know I can trust they are not going to waste my time or my money, and they're likely going to be honest about anything else.
The ability to listen is also very important to me when choosing a vet. If a vet can't listen, then what's the point?
I'm a little bit torn on the cold with animals part. On one hand, compassion is very important. On the other hand, I've been accused of being cold with animals because I don't coo, or squeal, or talk to them like babies.
We're exceptionally lucky to have a plethora of vets in our locality, when compared to other countries.
Very good question I have the same problem with mine