A player can choose to wear their guild's tabard, and even if hidden by costume, the guild name will show on the name plate, if you have those turned on. I think there may be some addons that track the names of players you interact with, probably from the death recap. But mostly it's like GlassHalfFull says. If you play on a campaign long enough, with chat on, you start to learn the "politics" of what groups, who are in those groups, and how they play.

i recognize guilds from the tabards

ball groups are extremely easy to notice because 8-12 people with the same guild tabard (which shows the guild in the nameplates) and it gets easy to remember

i could easily name off hand about 4-5 guild tabards i see regularly or are especially annoying ball groups (i cant do it on the forums though for obvious reasons lol)

Holycannoli wrote: »

Hmm I'll have to pay more attention. I've never noticed a guild name anywhere, tabard or no.

you have to have nameplates turned on to see the guild names

you know how NPCs are like:

NPC name
<general merchant> (in the case of guild trader NPCs, it would be <guild name> for the guild that currently owns that trader)

its the same format for a player

player name
<guild name> (if they are wearing the guild tabard, otherwise nothing is shown here)