We're accustomed to LVC, Wallach & Eastwood in their own tongue, and it seems completely artificial to hear them dubbed, it doesn't seem true to the character at all.
LVC has a tenor voice in English, but they give him a baritone in the dub. YOu don't need to drop AngelEye's voice an octave to make him menacing, actually it's scarier having him as a tenor because his voice is so normal. His delivery is very calm and unmelodramatic, but it's the way he phrases things - like the hissing of a snake - is what makes him so evil. You don't need him trumpeting like an opera singer to make you sweat.
I think Wallach nailed Tuco, the whining is part of the character. Tuco is always a couple of chess moves behind Blondie and AngelEyes, so of course he's always frustrated and always whining.
I don't think shading Tuco is true to the character, he's pure Id and all action - to try and convey a deep, reflective inner life for Tuco by shading his voice is out of character.
The voice and the face and eyes are all of a piece. You always lose something in the dub - unless it's the heroic job done by the dude who did Ramone & Indio for Volonte
Here's where we disagree. Tuco is not a blockhead, far from it. He can trace Il biondo (twice!) and could dispose of him were it not for Carson appearance; he also disposes of phisically superior Brega and of Mullock (twice). He is fast getting on to Carson's revelations. Sure, he has some comic traits: that is what render him the most complex character of the three and the most interesting. But it is this complexity that is not adequately served by Wallach monotonous voice. He is unable to slip from comdic to dramatic in the same phrase which really renders the character so fascinating. Actually I wonder how english-speaking listeners can appreciate the character given these rather heavy limitations. Then what is the brother's episode there for? And the dialogue with Blondie on the coach?
This is like Visconti's The Leopard. I feel that the Italian dub given to The Leopard is much better the Lancasters original voice.