[Hellstrom]

Are you only judging Intimidates declining DC from conversations with commoners? Because it would make sense for it to decline (or bonuses to increase) in those conversations as your level and/or notoriety goes up. "You better respect me..." works a lot better if you're notorious for killing dragons and have a talking sword.

To get more info I'd suggest you gain few levels with no notoriety increase and see if it declines for your character. Then, try dying, fugueing, and respawning with XP loss a bunch of times to see if the DC increases. Let us know what you find out... :D