I'm surprised that some people would say the concepts don't have the three characteristics. (Or did I read that wrong? Is it something more like the three characteristics don't apply to them?) I personally think that the concepts are among the easiest to see the anicca, dukkha, and anatta.
The concepts obviously change (i.e., someone understands them in a different way than I do). They're obviously dukkha (there are disagreements). They're obviously anatta (I didn't think up these concepts by myself).
One of the hardest things for me to see the characteristics (if I'm really honest with myself) would be the consciousness (formed by the aggregates). Though I can sometimes see the lapses (absentmindedness, the short period between being awake and the dreaming, etc.); and that this consciousness is what makes me notice the dukkha; it's still difficult for me to see the anatta (I still see it as a self, this awareness seems unique to myself, it seems singular, even though I keep on reading stuff that it's not, etc.)
Is this discussion more like a case of what would be the most useful way of applying these three characteristics? Like, the insights that you would gain from analyzing just the concepts would be considered weak, compared to analyzing the very aggregates themselves, because the latter would be more difficult to penetrate?
If that's so, then I think it makes a lot of sense... more than just saying that the concepts don't have the three characteristics (or that it doesn't apply, period), because that obviously isn't true.