I understand completely, there are many situations in which a man will say "no thanks.", one that has been exposed as women have become more open about their desires. The priapic nature of male sexuality has always been a myth.
I can't say I've ever actually said no, except those where cash payment was involved, but I have certainly pretended to be oblivious to certain overtures. Women take pride in their subtlty but word got back to me in several situations that my subtlety was not appreciated.