To me? Whenever I notice inconsistencies in others, including myself.. it's usually a sign that something that we do/say isn't quite in alignment of who we truly are/what we truly want inside..
Sometimes, I think inconsistencies have to do a lot with 'expectations' that people feel that they need to do for others, including themselves and ourselves.
So, it's usually a matter of social obligation vs. personal needs/wants?
I think that when we feel we 'need' something, the more likely the patterns of inconsistencies there are in our behavior. When we're at peace with ourselves? The more consistent we remain.
I think that since life is in a constant flux and that we tend to get influenced by our surroundings (social, situation, peer, family, etc), sometimes we veer off the wrong path, either consciously or unconsciously to avoid dealing with the pain.. Perhaps, those who are more inconsistent are dealing with the instant 'pleasure principle.'
I tend to be consistent overall.. In terms of inconsistencies in others? I'm okay with it, as I realize that we're all in the path to finding out about our true selves, each and everyday? We become so socialized that we lose touch with what truly makes us happy in the purest sense? Yah.. I think so..