I have to agree that certain visual aspects are entirely appropriate to base judgement on, like how well a person takes care of themself and body language. Fiasco, the overweight example can cross into that judgement, but I think it is unfair to form an opinion immediately. There are plenty of people in the world that have medical issues that keep them overweight, it's not necessarily about not taking care of themself. There are also plenty who abuse their bodies and in that case, it's appropriate to form judgements on what kind of person they are.
My biggest gripe is idealization based on physical attraction.