Because society is obsessed with looks above all else. When an unattractive man exhibits any sexual expression, he is automatically perceived as a degenerate pervert — not because of his actions, but because of how said actions come across to those who judge everything superficially. An attractive man behaving in the exact same way would come across as confident and sexy, as those are the traits they have already projected upon him long before he did anything. No woman wants to see an unattractive guy engage in anything sexual in nature, as it repulses them primally; anything sexual within their minds excludes nonchads by default, so it's appalling to them when they veer into such territory.