Theoretically, good kendo is good kendo and there should be no difference between the attitude and the technique displayed in keiko or shiai. Every keiko should be approached with sincerity and the objective of taking shodachi, (first point). You would therefore assume that shiai kendo at every level would look like the competitors’ everyday keiko – but it seldom does.
The obvious difference between keiko and shiai, is that in shiai there is more to lose, so intentionally or unintentionally; competitors become defensive. This does not just apply to less experienced players, but becomes even more evident at All Japan or World Championship level. Scan YouTube for kendo shiai content and you will lose count of the number of times that you see top-class kendoka holding the shinai above their men or in a modified kasumi no kamae to avoid being hit. Now you know that is wrong; I know that it is wrong; and believe me, they know that it is wrong, but they are not there to lose.
You can however see examples of shiai that totally reflect the principles of kendo that we try so hard to master. Typically, but not always, the competitors in these are older, more senior kendoka. The All Japan 8th dan championship and the final day of the Kyoto Taikai normally contain inspirational contests that typify all we try to achieve in kendo – good posture, strong zanshin and points won on seme and timing. If one of these competitors makes a successful attack then the other receives it with humility and good grace. I have a clip from a long ago Kyoto Taikai, where one kendo meijin acknowledged a point from his opponent before it happened. The other sensei had made a successful seme that clearly stole the centre, so rather than waste time by hitting men, they both bowed and continued to the next point.
Understandably, once kendoka ascend to the heights of hachidan and particularly hanshi, they acquire the obligation to display pure, honest kendo to the rest of us. Interestingly enough, these paragons are often the same people we saw ducking and blocking 10 years before.