Just for the record, the same 6.0 liter that has a (yes.. DESERVEDLY) bad reputation is/was used in school buses and other commercial vehicles and enjoys a solid reputation. The same motor. The difference is in the smog equipment, from what I understand. EGR, etc.. like others have said.
International made the DT444E, (7.3 liter) and they also made the 6.0. The 6.0 in the pickup trucks has new stringent smog requirements of 2003+. (commercial vehicles didn't)
Not making excuses, but if Ford wasn't forced to slap tons of complicated, crappy smog equipment on the 6 liter, it might enjoy have half the good reputation the good old 7.3 does. The 4 smaller valves instead of 2 big ones, variable vane turbocharger, etc.. well, those don't help.
Simplicity is reliability. (5.9 Cummins anyone?)
And yes, I own a mint condition, 7.3 Power Stroke truck. The newer, complicated, complex, sensitive diesel engines suck. (in my opinion)