I must confess that as a small child, I was deeply disturbed by the creepy surrealism of old cartoons of the "rubber hose and black bean nose" era -- the Fleischer Brothers were notorious repeat offenders, but the studios of Messrs. Disney, Warner, Goldwyn, et al., were by no means innocent. That style of art and animation has never been "cute" in my eyes; in fact, it is indelibly associated with a queasy frisson of eldritch horror that even the works of Mr. Lovecraft only seldom elicit.
As a result, when Sonic the Hedgehog resurrected the "rubber hose and black bean nose" style in 1991, my stomach lurched.
Thus, when I am browsing the various art sites I frequent and see Sonic-based art ... I never click the thumbnail. When, in my wanderings around the tawdry wastelands of Second Life, I happen across some hapless individual wearing an avatar in the Sonic style ... I go the other way. Very quickly.
It is, I assert, no reflection on the quality of either the art or the individual. It is wholly the style itself.
It is not so much an "Uncanny Valley" as an Unholy Abyss.
Oddly, the faux-retro stylings of the Animaniacs and their ilk don't disturb me at all. Despite their superficial resemblance to the antediluvian antecedents of animation's Golden Age, Yakko, Wakko, and Dot are proportioned, rigged, and animated in the modern fashion.