Nonsense. Take ownership of your feelings. Don’t put things on the date (“I’m not who you are looking for”, or “I’m not feeling the connection.”) Take responsibility, and tell the date that you don’t really like him enough to go on another date. If he asks why, don’t answer. It’s just a feeling. If you answer, he’ll find ways to fix your problems (that is, if he’s interested in you).
Be straight. Don’t make a guy wait through a few turn-downs to figure it out. Just say it straight. It saves everyone time and worry. Both of you. You can even say, “I don’t like you enough to go on another date. Sorry.” It gets the message across quick and clear, and saves you all time and mishegoss.
The reason why most people don’t say things straight, is that they don’t want to see the hurt expression on the other person’s face, or hear it in their voice. They don’t want to be thought of as a bitch or a ball-buster. Tough noogies. That’s life. Take responsibility. He might call you a bitch, but so what? Not everyone will like you, just as you don’t like everyone. But it saves so much time for both of you. It keeps him from coming back, and you having to say “no” over and over.
God! I hate it when women are wishy-washy that way. I don’t get it, either. Why not cut me off when it’s early on, and I haven’t invested anything in it, instead of waiting until later when I’ve tried and tried. It feels much worse, then. Unlike @Quagmire, I have experienced this. I guess he doesn’t ever ask out any women.