To folks less acquainted with facts on the issues, Trump manages in a very shallow way to appear forceful, authoritative and verbally agile. Hoping listeners can peel away that layer and notice the lies, evading of many questions, and underlying lack of coherent policy ideas.
Biden was painful to watch - he has declined visibly in the past couple years and he was never silver-tongued to start with. He seemed to struggle, often coming across as a grumpy old man, which obscured many valid points he made about his record v Trump's. The sense I had of someone desperate to get his words out and sometimes staring off in an odd way as if searching for an answer, and a suitable facial expression, is something I've seen in relatives on the cusp of dementia.
Trump has always lived in a narcissistic fantasy world, but can feign normality. Biden is a long term resident of the real world but now looks bumbling and to be feeling his way through fog. I fear that undecideds who do not prize facts and evidence will be fooled by appearances and Trump's knack for hammering on his narrow selection of American Carnage themes.