I’ll start with the Porsche 997, the 996 looked alright imo, but it looks “like a 90s Porsche”, the 997 made it look sleeker and more modern. Still looks good today.
As for cars that looked worse after a facelift? Maybe the facelifted 6th gen Camaro? The 6th gen looked great pre-facelift, but they did something weird with the headlights and now it looks so-so…
The refresh on the previous generation Camry was a massive step backwards. 20012-2014 was very sleek and classy looking. 2015 they made it extremely ugly looking and somehow sales went up. Definitely the worst refresh I can think of.