How people look is quite complicated I think. We all know some people photograph well, I think the saying is "the camera loves them." It doesn't love me, I had a photograph for something at work once and the photographer said he'd photographed pieces of wood that were more animated than me. It was harsh but true except if I have a baby in my arms, then I am smiling and relaxed presumably because I'm concentrating on the baby not fretting about the photograph. I can honestly say if you put two photos of me side by side one on my own and one with a baby you wouldn't think it was the same person.
Also some people seem to wear clothes well and others not. I heard an actress once who was talking about being a child star in Hollywood. She went to the studio school with Elizabeth Taylor and she said ET never had a hair out of place and at the end of the day looked exactly like she did at the start. I felt a bit sorry for her, thought she must have been drilled on her appearance and not allowed to play and then my son started school. Lovely little blonde girl went in at the start of the day looking like a model from a catalogue. At the end of the day she looked the same. Other kids have paint and dirt on them, white knee socks rolled down etc and again I assumed she must be a quiet little thing who didn't play. I volunteered at the school and soon saw she was a lively child who joined in with playground rough and tumble with the best of them. I assume she had the same bubble round her as Elizabeth Taylor.
I think Johnson hasn't got the bubble or maybe his dishevelled look is deliberate and I think that is what irritates a bit, the idea that he might deliberately look like he's never seen a comb and his suit isn't a great fit. Next to Biden, Macron, Trudeau to name a few he just doesn't look that smart, I think partly due to them being taller (I think) and slimmer and maybe partly due to being as good at photographs as me or maybe because he cultivates that look.
I don't like a lot of what he's done, his appearance isn't that big an issue.
Back to the original I think Jill Biden looked great and the camera does seem to love her.