While I'm on the subject of thinking...and not thinking...and being able to feel it either way...I can also feel your cabeceo...
To me, it is a big, big, big, really big, "no-no", a faux pas - to cabeceo or otherwise scope out other leaders while you are on the floor dancing.
It's only happened to me once, and she has been blacklisted. She knows that I know. She was surprised to find out that I could tell. That I could "feel" her doing it.
First, it tells me that she is thinking...thinking about something else besides dancing with me. I want to dance with followers who are "there", "present", into dancing with me. If they are taking the time out in a dance (or tanda) to be scoping out potential leads, or worse, actually engaging in cabaceo, then they are not there with me.
Engage with me, not with other leaders.