So you are suggesting that Eve looked more beautiful after sinning, and that is why Adam ate the fruit? That is the first time that I've heard of that idea and now I'm curious, where did you hear that idea?
Now, don't get me wrong, I wasn't there. So I can't speak with absolute authority. But, based on what I know, I'd say that that is not very likely. One reason is that there is no evidence in the Bible (to my knowledge) that would suggest that. And, looking at it from a practical standpoint... what are the implications of having a fallen person look more attractive than their pre-fallen state (especially to a pre-fallen Adam)? A further implication would be that woman's beauty is the reason why man fell, not for any other reason. And that, I think, would be harsh towards women and imply a sense of superiority/arrogance for men. After all, it puts most of the responsibility on Eve... and I think that it is clear that they are equally responsible because they (probably) ate the fruit for the same reasons.
Well, there's my two cents.