The Siberian Siren and other sledges

Caught a little of the Sharapova-Frazier tennis match last night and it has left me with 2 burning questions: why is it ok for commentators to pass comment on the looks of female players and why is it ok to do this when the player in question is only 17?? Sharapova was described as the 'Siberian Siren' among other things while poor old Amy Frazier got the cold shoulder. Admittedly, Amy is in the Lindsay Davenport school of tennis players, as opposed to the Kournakovas but really, none of this should be an issue. I know it's been going on for ages and I know Sharapova is just the latest in a line of Stepford-wife type player coming out of Russia. But if such comments as were passed last evening were said about a mate's 17 year old daughter I think the commentator would be looking for his nose somewhere down his throat.