A random link pointed me to the Wikipedia page on Rob Liefeld.
It's fascinating reading, tracking his ups and downs and critiquing his art and work style. Of particular interest to me:
While Liefeld's artwork, particularly in his earlier efforts, manifested a striking design sense, his shortcomings were initially covered up by strong, experienced inkers. As Liefeld was able to exercise greater control over the form in which his work appeared, those shortcomings became conspicuous, and defined the public perception of his work.
Though this makes sense, it hadn't occurred to me that inkers from the experienced Marvel pool would naturally correct his more outlandish art issues. Pencilers complain sometimes about having their work butchered by inkers, but inkers, in turn, are used to having to correct the mistakes of pencilers (there's a good spoof "So you want to be an inker" ad by Terry Austin in one of the early issues of Marvel's long-gone humor comic, What The?! that deals directly with this).
Plagiarism. Rob Liefeld created several super-heroes heavily inspired by already existing ones, such as Captain America and Avengers look-alikes. He is also accused of copying panels from other comics .
Then there's a link to this comparison page. These examples, especially the flying thing which may be a SHIELD heli-carrier, appear to be close beyond coincidence.
It brings to mind the more recent artistic misstep committed by Mike Mayhew for Marvel's House of M, in which a photo of the king of Spain was turned into a portrait of Magneto. Now the Spanish royal family is looking into the issue. Do they have more or less clout than Steranko or Lee? Probably.
As one poster in the thread I"ve linked says: Imagine what kind of Hell would open up if an artist took a photo of George W. Bush and turned it into a portrait of a terrorist to promote their Summer line. Better yet, imagine if he was an artist for an European publisher.