I just read up on Warduke in a Dungeon magazine. Anyone who's watched the original D&D series is aware of who this guy is, but anyways he's written up as an 18th level fighter, but he's a CR 20. Why? Because his WEALTH is that of someone at lvl 20, not 18. This means that his CR went up by 2. So if that's the case, then the CR 14 Rogue 7/Thayan Slayer 7 is actually CR 16 or 17 because he's worth 90k. Add another 10k worth of items to him (not all that hard considering how many slots he's still got open, and the picture could easily depict other items like a mask or cool boots) and he'd be that CR 17.
The same goes for the PCs in the D&D series adventure book. Hank, Sheila, Bobby, and the others all have a wealth that makes the ECL 9, not the lvl 7 characters that they're written out as. Now, I don't care what anyone says, but I honestly think they're lvl 9, not ECL 9 because of the weapons. I've watched that series countless times. They're mid-level, at least.
I see boss characters getting away with it, but it still makes it iffy. It just makes them harder to fight, and I do believe it should affect their CR. But that doesn't mean I won't take what's written with a grain of salt.