Two examples...
-One of my guilds has been at 499-500 members for the last 3-4 weeks. Once or twice a week someone drops and the spot immediately gets filled. Its consistently listed at around 450 members. Right now the guild has 499 members but the guild finder only shows 449.
I checked the roster- maybe the game was smart and not showing inactive members? Or those 50 spots were pending invites? No and no. No pending invites, around 20 people who've been offline for a month or more.
I also joined another guild today that's listed showed around 270 members. They actually have 370.
What gives?