What is the ruling on looking at someone who commits evil deeds, such as smoking and letting one's garment hang below the ankles, and is it forbidden?

If looking at a smoker or a person who lets his garment hang below the ankles is unintentional and not with the intent of sitting with them, there is no sin in it, by scholarly consensus. As for sitting with a smoker or a person who lets his garment hang below the ankles, it is not permissible by choice except with the intention of admonishing them and inviting them to abandon what they are doing. If it is not for that purpose, then it is not permissible except out of necessity, while disapproving in one's heart, due to the Almighty's saying: "And when you see those who engage in [offensive] discourse concerning Our verses, then turn away from them until they enter into another conversation. And if Satan should cause you to forget, then do not remain after the remembrance with the wrongdoing people." (Quran 6:68) And His saying: "And He has already revealed to you in the Book that when you hear the verses of Allah being denied and ridiculed, then do not sit with them until they enter into another conversation. Indeed, you would then be like them." (Quran 4:140) Thus, the listener who does not object is a partner to the doer, and whoever witnesses a sin and dislikes it is like one who was absent from it.