My partner always tells any organisation or charity who knocks that the door that we don't give anything to anyone without doing research in to them first so if they have a leaflet, we'll look through it and go from there. A lot of them get pissy about it and leave. I recognise that they almost certainly get paid a commission for each sign up they make, but it's just not something we feel comfortable with. In my last flat we had two guys knock and try to sell something or ask me to donate (I can't remember which now), but despite me answering the door and it being MY flat, they both refused to talk to me and talked past me to my partner who was sat on the sofa. It was so fucking rude and even if they had a hope in hell when I first answered the door, it was well and truly gone. My partner ended up telling them we do research first etc but that it was my flat anyway and he was just visiting. They scarpered pretty soon after. Don't get me wrong, I didn't want to be wasting my time talking to them anyway but it was a slight surprising attitude.