My observations so far:
Before Sep 18, when it was unclear where each boarding line terminated exactly, I used to get a lot of:
"Excuse me, is this Group 1?"
Nowadays, because the pre-boarding area is mostly undefined, there is a lot of up-and-down checking out of the scattered people:
"Hmm, yeah, she looks like she's used to flying a lot. I bet she is 1K."
and
"Yep: shorts, tanned, baseball cap. He's definitely got that GS 'look'."
So you can tell where all the GS and 1K are hanging out, and you just congregate there too.