I have never been with a man that has taken viagra. I like to think that I am his viagra.
Or so you think. Not trying to be an ass-wipe here (we've had our falling out) but you cannot honestly know what a guy has done to get hard for you. You can only hope you are so hot that he wouldn't need to use artificial means to stay up for the duration. Men's sexuality is more complicated then you know apparently.
Just so you know, I am not attacking you. I am merely stating the facts. A guy getting turned on is not only about you, it is about him too. Do not make yourself out to be the erector of men's dicks, because hot or not, you are not.