I mostly care about policy and character, because we don't have a wide enough selection net to choose people who best match our outlook on all the issues we care about. Perhaps this means I think we should not even have a President and directly elect e.g. the head of the EPA. But until then, character and general decision-making are critical to consider when voting. But politics? The posturing and personality of leaders? I don't totally get the importance of it to me, an average person. I'm sure a campaign manager would care. But why would I?
That being said, I think some of these professional politicians are occasionally wrong about material facts of their profession. I see them acting as though the only thing they care about is getting votes, and then doing things that don't maximize that.
The second worst political error is Trump downplaying the coronavirus, specifically because it is only terrifying Russian-roulette-levels-of-dangerous for the very elderly. Even if I was reassured by that, I think those elderly people wouldn't be, and they vote quite often. If only young people put themselves at risk the pandemic will continue to burn through America, and I think people have sort of wrapped their head around that not being good for them, even if they themselves can lower their risk.
The worst, though, is Trump not unequivocally condemning violent neo-Nazis chanting "Jews will not replace us". It's sort of a strange thing, right? Because those people suck, and conservatives dislike Nazis just as much as anyone. There aren't that many of them, so he won't lose votes, and it's clearly an embarrassment for him. No normal person understands why he won't say they're bad, and no well-adjusted person understands why a political leader would hesitate from saying 'don't be violent'.
[Edit: there are some people saying he did denounce white supremacists – weirdly, I find that, even taking their readings as absolutely and completely true, I wouldn't need to change anything about the previous paragraph. See more details here, although, as you might surmise, if the alternative narrative wouldn't lead to me writing something different, I guess I'm not sure it's all that much of an alternative. Particularly if he "would do anything", and "wants to see peace", not saying "don't use violence" is even weirder. Like, you should at least try saying that, when specifically prompted, it might help with that goal of peace.]
I think people don't realize that a meaningful chunk of Biden's projected lead now could be stolen away if Trump stopped making these specific, factual errors in how to campaign. I don't think he believes anything, this isn't driven by ideology, it's an error, and once corrected (if it ever is), the polling gap will shrink. If it doesn't, this must have been one of those things that never mattered, but I think the professionals who pay a lot of attention have been skeptical of that. Condemning bad people, often much harsher than they deserve, is a political contest as old as time, and very, very likely to help the politician.