When a guy says, "I want you so bad," it generally indicates strong desire or attraction towards the person he is addressing. It suggests that he has intense feelings of physical and/or emotional longing for that individual. The phrase is often used to express deep romantic or sexual interest in someone.
It's important to interpret such statements within the context of the relationship and the individual's intentions. Depending on the situation, it could be a genuine expression of affection and interest, or it might be a statement made without sincere intentions. Communication is key in understanding the true meaning behind someone's words and ensuring that both parties are on the same page regarding their feelings and intentions.