Lesson 1 Sometimes a person who has been to a strange city or community feels that s/he hasnt been treated properly and consequently disparages that entire city or community. This is a serious violation of lashon hora since there are a large number of people being spoken about at once.
Lesson 2 - speaking about a community contd. If you do think there’s an issue going on within a community (i.e. lack of hospitality), you are allowed to speak to a competent authority if your sole intention is for that person to constructively rebuke that community. All the laws of speaking for a constructive purpose apply.