Well, I'm getting more than irritated with this whole "sneak" issue. It appears I don't have a high enough sneak skill to get past Fathis Aren. And it seems that I can't find a trainer of sneak either! None of the dialogue options come up for Othrelos or Mirabelle Monet (mid-level trainers). I've taken off all my sneak gear and have a base Sneak of 45, which should be within their realm of training. The guide says that the dialogue has to be triggered by someone else -- one would think, having gone through 3/4 of the Thieves Guild quests, it would have happened by now???

45 is not the end of mid-level, 70 is.

and, i think, the game do "scale up" ability score to match yours. i mean, i am sneak 100, can't be better, but still got detected like a crane among chickens.

In one of dark brotherhood quest where i am suppose to sneak into the house to kill the owner while sleeping. this bodyguard of someone else has a bodyguard of himself and this bodyguard never sleeps and he spot of right on everytime i sneak into the house.

It's probably true about the leveling up. But Othrelos or Mirabelle Monet ARE mid-level trainers, so with a Sneak of 45, I should fall within their range.

The ranges are:

Low Level: 1-40
Mid Level: 41-70
Master Level: 71-100

I'm not getting the dialogue option at all -- which means of all the people that I've talked to, it hasn't been triggered. My complaint is that if I make it to the advanced thieves guild quests (with only 2 left to go), and in the course of these quests, still haven't triggered that dialogue -- that's a serious game problem and it doesn't make any damn sense. An experienced thief in the guild would certainly be offered a chance to train by now!