You can't help it to an extent. If a girl is attractive then you're more likely to try and strike up a conversation with her, just have some form of 'interaction' with her even if its only in a brief encounter. So boys are friendlier to attractive girls.
The downside which probably gets on attractive girls nerves is, everybody has days when they have something else on their mind and they don't want to be bothered. But for an attractive girl she is always kind of 'public property', if she sits down in a lecture on her own, some guy will come and sit next to her and start a bit of chat. If she's out at a bar with her friends, guys will come over trying to chat her up.
In my social group of friends there's a really attractive girl (modelesque) and although she's very down to earth as a person you do notice how she gets treated differently by people. If we're walking through town guys shout stuff at her out of cars, if we go into a bar she gets treated like a celebrity, guys are always coming up to her trying it on and if she wants a quiet night she just has to politely get rid of them one after another. When I get invited to house parties by male mates, they are always badgering me to get this girl to come along because they've seen her on my facebook and they reckon 'with a few drinks down her anything could happen'.
So it obviously has its inconviences. But those are outweighed by the fact that when she does see a guy who she's attracted to and wants to talk to him, she can approach with confidence knowing that she won't get rejected.