"And the men rose up from there" (Genesis 18:16). Because Abraham was righteous, they were not called angels; and the entire time that they were with him, Abraham did not suppose that they were angels, and therefore Abraham went with them to send them off. "And they looked down upon the face of Sodom" (Genesis 18:16). Every place where "looking down" (hashkafah) is stated is for evil, except for "Look down from Your holy habitation" (Deuteronomy 26:15); for because they give terumot and ma'asrot to their owners, the attribute of punishment turns into blessing.
Why the Visitors to Abraham Were Not Called Angels
Midrash Aggadah, Genesis 18:16
ויקמו משם האנשים. לפי שהיה אברהם צדיק לא נקראו מלאכים, וכל זמן שהיו אצלו לא היה אברהם סבור שהם מלאכים, ולפיכך אברהם הלך עמם לשלחם: וישקיפו על פני סדום. כל מקום שנאמר השקפה לרעה, חוץ מהשקיפה ממעון קדשך (דברים כו טז), שבשביל שהם נותנים תרומות ומעשרות לבעליהם חוזרת מדת הפורעניות לברכה: