So for me is very much the "vibes" I am sending out. And I have recently done just that: went to a milonga, had a look at the ronda, realizing I would not be able to engage and left. I didnt't even put my shoes on. And I was perfectly fine with that. So my point is: the responsibility is mixed and quite a lot resides within ourselves.
Being a 'newbie' I haven't gotten to that point of walking in, assessing the scene, and leaving. Plus, it helps immensely to have an experienced dance partner who's my life partner (girlfriend). So, we really don't have to put-up with any "vibes" from others, and if there are any 'negative vibes' out there neither of us pays attention to them. Besides, if we get any "vibes" from others, we have each other to dance with, and can do so the entire milonga if need be.
Going into any milongas with an open mind has been my goal, whereas my GF sometimes has other things she's thinking about, namely who the host is, who else is going to be there, and whether she'll dance with others.
What I'm seeing from her is she seems to have certain leaders who never ask her, so maybe there's a "vibe" that she's projecting, or what seems to be the case, she intimidates them. We've also speculated that some leaders are reluctant to ask followers who arrive at a milonga with a partner, and they pick those PYT's and partnerless followers.
Then there are those leaders who ask her that she's not as interested in dancing with due to many reasons (hygiene, poor dancing skills, mushy-feel, etc.), but does so as a courtesy since she has known them a long time. Accepting requests from those leaders comes from years of '
taking-what-she-can-get' after sitting during milongas when she wanted to dance, and her 'accommodating' demeanor.