Also, the term "self-esteem" is somewhat problematic because the underlying existential position it's supposed to label seems to vary too much. Sometimes it's defined as simply having a very positive image of the self - in a way that even narcissists can have very positive images of themselves - regardless of how much unconscious shame is actually polluting a person's ability to take full responsibility for their own interpersonal footprint in the world. Yet other times it's defined as the condition of having a positive self image unsullied by narcissism - as if the former isn't real self-esteem.
The way I've been looking at it is a lack of faith in one's own abilities/skills. If I'm getting more positive feedback about something than I think is merited, I take that as a sign that I probably don't have as much faith in my own abilities/skills as I'd thought. When I was younger I didn't give this lack of faith much consideration (because the prospect of being 'that person' was so loathsome to me), and learned the hard way that it's important to learn to defend myself where I merit it because hoping/depending on someone else to always be there to do it for me was basically putting my fate in others' hands - which isn't fair to me, and it isn't even fair to others. I think I believed that if I did my best to be who I'd want to know (or to be the best employee I'd want to have, etc), then there would always be someone there to help defend me when I needed it - and life just doesn't work that way. So I wished I'd learned at an earlier age how important it is to have sufficient faith in one's own abilities/skills and even in one's own character.
But anyway, where I get praise from several sources on something, I take that as a sign that I'm not giving myself enough credit. I generally do tend to write off isolated praise - and it's not even that I write it off so much as make a mental sticky note, something like, "this person (considering the whole I know of the person as the source) said this thing." If I don't get that kind of feedback again, it will likely fade into oblivion.