As I've recently gotten involved in some ongoing arguments on the old Lee-Kirby credit thing, I've decided to post a few of my observations here as well, starting with this one:
...none of the stories Stan Lee tells as to the origin of characters he originated are any more far-fetched than those of Kirby.
Remember how Kirby said he came up with the Hulk? Seeing some news story about a woman lift a car off her child, or somesuch. This is what I call a "foxy grandpa" story, because it makes gramps look really clever. Kirby doesn't mention any other factors in his creation of the Hulk-- not any suggestions from Stan about making the Hulk look like Frankenstein, nor whether he Kirby was aware of Dick Briefer's use of that character (I've heard someone claim JK knew of DB), or any influence from THE AMAZING COLOSSAL MAN.
Lee's spider-on-a-wall for me is not an insidious credit-hogging ploy. It's another "foxy grandpa" story, which we only know to be untrue because of the testimony of Ditko and a few others.
Consider too that by the time Spidey got popular, Stan probably didn't remember particulars as to who did what any more. Of course, even if you'd asked him at the time about Spidey's true genesis, he might not have cared to admit having derived any part of it from the Fly, given the reputation of litigious Archie Comics.
Did Lee hog credit at times? Probably, but you've also got to remember that in the 1960s nobody cared about the fine details of who did what but a handful of earnest fans.
Kirby's descriptions of how he came up with stuff are of a piece with Stan's; lots of generalized metaphors with very few details about corporate or cultural influences.