Yeah. So. First thing someone does in Riften is talk to me about how the Black-Briars are connected with the Thieves Guild. I'm wondering why he tells this information to every stranger that walks into the town, especially since it's not something that you'd want the Jarl to learn about. I go talk to the Jarl, who tells me that the Black-Briars are 'investigating' the Thieves Guild, and I wonder why I can't tell her that they aren't. I see if I need proof, and break into the Black Briar's house to get those letters off her desk, which I think is proof. Nope, still can't tell her about the corruption right under her nose. So, instead I decide to see if I can talk to Maven about it, get a confession. Well, it wasn't hard, since she has only one conversation option and in that she admits without a second thought that she has connections to both the Thieves Guild AND the Dark Brotherhood. Imagine some stranger walking up to you in the street to talk, and you were the top man of a criminal organization that specialized in assassinating people, or someone who hired them frequently. Would you tell that stranger without getting to know them, first? Most likely, you wouldn't tell them at all. But the NPCs in Riften seem to think it fitting to tell everyone that they're evil people, yet you don't get any options to get them arrested. No quests to root out the Thieves Guild or clear Riften of it's corruption. This is a huge immersion breaker.