First of all, whilst it is difficult to think of Dr Doom, the Red Skull or Mephisto, as being a "good guy", the definition of what constitutes a "bad guy/gal" in the Marvel Universe at least in the popular MU mind, is often based on sheer prejudice as much as it is concrete reputation(pace Spider-Man vis a vis the incessant Daily Bugle campaign against him,or social groups like mutants(the X-Men/ New Mutants), the unfortunately(to put it mildly) titled Inhumans or simple sheer physical appearance( pace the Thing and to a lesser extent the Hulk), not to mention supernaturally based groups such as vampires or werewolves.

Terry

Norman Osborn.

The readers or to be exact the vast majority

Yes, but at least in the MU, prejudice seems to play a larger role than anybody realizes(pace the obsessive campaign against Spider-Man by the Bugle publisher J. Jonah Jameson), or that against certain superhuman races(pace mutants and to a lesser extent Inhumans). Despite all that superheroes (mutant and otherwise) have done to defend and protect the earth from bona fide villains(including Galactus), WHY then does popular fear and distrust seem to inform everything they do?

Terry

Marvel have totally lost sight of what makes a villain a villain, and that lack of vision is expressed through a continually incompetent in-Universe civilian populace.  
 
New Yorkers cheering Norman Osborn? Come on. How did that state not sue for libel?