I believe it is in the modeler's nature to see mostly, if not only, the flaws in his own work. Only we know what we thought it would look like when finished, and how often does the completed model match how we imagined it at the start?
When we see someone else's work, unless we just finished, or probably currently building, the same kit, we won't know really how well that other modeler did. We don't see it in pieces as the construction takes place, we don't see what was screwed up and needed to be fixed.
Of course, we can critically check the painting, weathering, etc., stuff we all do and judge that work compared to ours.
But, will we catch the crooked decal, the kind of goof that looms so large to us on our current model? A similar goof that we can glance over without a second thought on someone else's build?
We should be our own harshest critics, that's a great way to learn. At the same time, there's no need to beat ourselves up needlessly. We may never know, but the guy that built that great model we saw in the magazine, may be kicking himself over some part of that build too.
Keep it fun.