First of all, I think that there's a difference between an athlete and a “famous” athlete. Being an athlete in high school, it would be more acceptable for them to partake in things people their age do because being a professional athlete is not a sure path they'd take in the future and they are not in the limilight. However, being a professional athlete, those who are already in the public eye like Michael Phelps, ought to hold a higher standard. This is because many people look up to them, especially those who are younger than them. We live in a media-driven society so whoever we see on television, hear on the radio or read about in publications, we tend to aspire to. Rarely do we ever aspire to people who hasn't claimed their fame. I think that it was good that Phelps apologized because this shows true professionalism. If he ever did this again, then it's his own frailty if people look down on him.
When I read Kenny's post, an immediate example came to mind-- Vanessa Hudgens. When nude photos of her circulated the internet, many people, especially parents were worried about who their children were looking up to. Hudgens is the star of the famous Disney film “High School Musical” which many children are avid fans of. Disney movies are mainly family-friendly so when the photos emerged, parents were worried about the not-so-wholesome image of Hudgens. It's the same with Phelps, many young swimmers look up to him so any inappropriate behaviour of his could turn someone off.
In general, I think that famous people-- whether they be an athlete, celebrity, etc. should set good examples. Whatever they want to do in their personal lives should be in their own discretion. They chose fame and being in the public eye so they should be aware of the consequences it would bring them if they did something inappropriate. Lastly, claiming fame is their opportunity to advocate some sort of positivity in the world and use fame in a good way.