People, I think I have finally "found" what most people consider so "bad" about multi-effects units' "dirt" sounds and presets, considering that they had been setup well.
If we trace amplified electric guitar playing back to the 60s, we will find that the overdriven guitar sound was but a previously deemed "undesirable" byproduct of a tube guitar amplifier circuit's inability to stay "clean-sounding" when the volume is turned up. It was practically an accident, a flaw of sorts, and yet half a century later it is deemed the definitive rock guitar tone. The "disorderliness" that the overdriven sound practically stands for was what drew many famous guitarists to the electric guitar in the first place. Things like controlled feedback, fuzz, singing sustain, and EVH's "brown sound" would never have been developed if amps back in the day were not made to work too hard. The "magic" that such a setup brings with it is universally recognized.
Now, with amp modelers, the primary goal is to capture that sound, except that the sound would be the same at lower volumes. For those who wish to preserve their hearing, this is good news. While generally we consider analogue effects to be superior to digital all-in-one boxes, it cannot be denied that such devices can also be made to sound great. However, digital effects, at least in my observation, seem to have this particular tendency to sound too "studio-quality" and "predictable" that all the thrill and interaction that an overdriven amp brings into playing guitar is taken away. The only way I could describe it is like having a recording sessions every time one plays in a gig, and whatever is coming out of one's speakers is but a monitor out signal of a mic'ed amp. It can sound nice, but it will never be as "alive" and "dimensional" as an amp moving serious air with big-a$$ loudspeakers.
