Hormones & friendship

Should you trust a guy who lied to you just to get into your pants? My friend, who has had more than a fair share of bad relationships, thinks “YES!” Her logic, a little convoluted but sane, is below:
Invariably any new acquaintance starts with a degree of amount of flirting. Most men lie, cheat or deceive just to get into women’s pants. The lies could be harmless like boasting of your success, power, wealth or something more malicious, but it will always be there. Some guys play the short con by saying that they love you or want to marry you at first glance; some play the long con by befriending you before nudging you to sleep with some, but the con are always there. If you are lucky, some guys who start with a con but end up with having genuine feelings for you. In short to any virile guy, any attractive woman is a game that he is biologically programmed to try to win by bedding her.
The real question is what happens after. Some zip-up and leave and should be forgotten, but the ones who stay back are trustworthy. Since they don’t have a reason to lie anymore, and the girl has nothing more to offer only genuine exchange happens after a night in the sack. Hence a girl should ignore whatever lies a guy has said when you first met him and focus only on the future.
However it does not mean that you would repeat the same mistake by having a second night of revelry. After a age it is easier to burn bridges then to create new ones. There is no reason to discard a potentially healthy budding platonic relationship because of a bad kick-start. Hence probably my friend’s advice is for guys who want to move on and should not be generalized.