I believe all of the guilds in-game require a dialogue to join — you can’t join accidentally — except for the Thieves Guild. When I started ESO, on my templar I didn’t loot containers in occupied buildings, even when not labeled as stealing, because I assumed it was. But I did take from a thieves trove, thinking that it was taking stolen goods from bandits so…
Now it wouldn’t matter, except that some NPCs identify a character as a thief presumably based on this. Some of my characters would like to pay their penance and have this stain removed from their record!