There's plenty of skinny people who drink nothing but soda, eat nothing but fast food and suck down a ton of junk food but due to the fact that their bodies process food extremely well, they maintain at a healthy weight without the need of exercise. These people are every bit as unhealthy as their obese counterparts, but they remain unscathed due to the fact that our hatred is based on visuals alone.
This isn't generally true. If you calculate their calories and their daily activity, they end up being thin for a reason. Not saying their diet is healthy, but there's a reason they are not fat.