First off ladies, understand this: as much as you berate him, appreciate the effort. At the end of the day it takes a certain amount of courage to walk up to a woman and strike up a conversation, so even if you are planning on shutting him up, show him that the effort is appreciated. You don’t want to completely discourage him from ever making a move again.
Secondly, do not lie. Even if the man in question is absolutely hopeless at picking up on subtle clues of justified rejection, do not lie to him just to avoid the situation. If you show gratitude for the initiative and are honest with him that is something he can deal with and in turn appreciate. With that what you really are doing is protecting yourself from what can be the horrible side-effects of rejection. Being gracious always, always pays off.
There are few qualities superior to kindness. If you are kind and gentle while getting your message across, there really isn’t anything quite like it. Put yourself in his shoes—gone are the days where men are the only ones to make the move (though as much we’d like to think otherwise, they are the dominant initiators.) If at some point or another—whether it’s a simple case of concentrated eye-contact or whether you’ve straight up walked up to a hottie and asked for his digits, you know it’s nerve-wracking and not exactly a situation you’re thrilled to be in. There is always a chance of rejection and if that must be the case, wouldn’t you like it to be delivered with some degree of kindness? It doesn’t mean you have to misguide them. ‘No’ can be said with some softness too.
There is no good enough motive for you to give him a logical reason for your decision, because let’s face it—this is not about the weirdly short ankle length denims he insists on wearing or his strange mish-mash uncultured eating habits—sometimes you feel the chemistry and sometimes you don’t—so don’t make him feel any worse than he probably already does by giving him a laundry list of reasons that have driven you off. Keep it simple, keep it real and keep it torture-free.