I will usually let them know that they would get better results if they tweak what they are doing a bit. Thats if they are hot. If not I could care less...
Bro, have you read all the threads from the hot chicks here bitching about guys talking to them at the gym????
I guarantee you...Even if you have her best interest at heart...She will atleast tell her friends some jackass was hitting on her at the gym. Waaaahhhhh
My advice...Snub her. It will kill her. Then, be extra nice to a chubby girl, or one thats less attractive. They my friend...will appreciate it. (and possibly reward you )