The One Line Disclaimer

I have a close younger guy friend that I will Lil Brother. Tyler, if you're reading this its not you.. ha ha.
Ok, Lil Brother has been seeing this girl who he admits is a "placeholder". Basically, a chick he's seeing while he's meeting other chicks and waiting for one he really likes. LB has been seeing an awful lot of this girl, for a guy who just wants to date and just got out of a relationship.
Recently he told me she's been acting "like they're together". Now this surprised me. I said, "Well, have you told her the deal?" He says he told her he didn't want a girlfriend right now. Except he said it 3 weeks ago. And since then he has met her kid, slept with her a bunch of times, introduced her to his sister on Christmas Eve and spent Christmas with her. Day after Christmas she wanted to spend the say with him too, to which he says, well she's acting up again like we're together.
He told me this at work on Monday and I completely jumped in his shit. He said well I told her I didn't want a gf. I tried to explain to him that the one line disclaimer tends to get voided if you start to spend all kinds of time with someone. He asked why. I said because your actions are telling her something else. At least if he distanced himself she wouldn't think any more than what it was. He said, "I'm not like those guys you've dated. I'm a nice guy." But that's where he's wrong. His actions are exactly the douche-baggery of those other guys. It would be different if he owned it, but he deludes himself into thinking he's not which I'm sure other men have as well. He doesn't understand he contributed to the problem of her thinking anything funny.
So I brought this particular notion to ML, who is my co-worker and local thought-provoker. His theory is people who do this fall into 3 categories: 1. Those who use it as a guilt free reason to use other people, 2. Those who really do want a gf/bf but are too much of a wienie to walk the walk of free wheeling loner-dom and, 3. The honest to goodness hippy-Buddhist who doesn't spend the time and never leads anyone on.
ML seemed to think that most people fall into the 2nd category. I said maybe people as a whole, but single men are clearly category 1. Every woman I know has fallen for this trick at least once if not many times. I myself have been a sucker for this as well. Red recently coined the term "The MMC" after respective ex-lovers who have pulled this.
This brings to mind, whose responsibility is it to call out the bullshit? Is it the woman's? Most of us haven't realized we've been duped until the subject of togetherness has been brought up, and we are told, "well I don't know why you would think that because I told you I didn't want a gf". I joked with Red, that maybe I should remind myself of the contract I have with myself often. This is how I know I've been hanging out with too many lawyers (jk Weez, DN, ML, BPup and whoever else reads this!). As an example of the humor I told Red the next time a guy tells me the disclaimer up front, the second he starts wanting to see me, texts me, calls me and wanting to come over, that I will tell him his actions effectively voided the contract. That he either is dating me for more potential or isn't seeing me at all.
Too bad this is much easier to do when you don't like the person all that much. When you like someone, you WANT to see them, and it's impossible to tell if the person who is calling you and wanting to see you isn't Disclaimer Guy.
What say, you faithful readers?