I'm not sure that clarified too much for me, but I haven't mastered all the FAA docs yet. Basically I got this ...
Bad ad:
I'm going on spring break this year and am looking for someone(s) to share the ride & fuel cost. Email me your location and I'll pick you up on the way.
(possible lack of commonality, hold out, & charter)
Marginal ad:
I'm flying from HHR to Las Vegas this spring and have want 2 people to fill the seats for 3-way split of expenses.
(possible lack of commonality & subsidizing?)
"Good" ad:
I'm flying from HHR to Las Vegas March 22 to gamble, party, drink, and be merry. I have 2 open seats.
(established commonality)
Am I close?