Not normally in on the mirror finish and anodising of course changes all this if you don't remove it so very few things are candidates.
However I do clean, scrub and derust anything I can to the fullest extent possible.
Some things do get an aggressive scotchbrite and polish workover, a few things do get sanded and then polished close to mirror.
No real examples and most things only really shine in before and after pics.
Chrome is my big thing and now with evaporust it can be brought back better than ever and if not can still be made presentable bare metal and sometimes polished up a bit.
The polished crank looks great.
And so long as the the mirror doesn't outshine the rest of the bike to much its all good, can't really have bad form on your own bike.