All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.
As for mere laughter about the reality of the bad condition of the country – as you mentioned regarding the dirty condition of the streets and so on – and mocking this, then there is nothing that forbids it or makes it unlawful; so it is subject to the original ruling on all things, which is that it is permissible.
As regards the jokes: if they are true and do not include backbiting of a particular person, then there is no harm in it either, but if it involves backbiting a particular person, then it is forbidden.
Also, if the joke is a fabrication and a lie, then a group of scholars explicitly stated that it is forbidden.
Ibn Baaz said, “Joking when speaking if it is true, then there is nothing wrong with it, especially if one does not do so often, and the Prophet used to joke, but he only said the truth. However, if one jokes by telling a lie, then this is not permissible, because the Prophet said, ‘Woe to him who lies in his talk to make the people laugh, Woe to him! Woe to him!’” [Abu Daawood, At-Tirmithi, and An-Nasaa’i with a good chain of narrators]
As for the jokes that are forbidden, are they minor or major sins? Then what can be said in general is that lying is considered a major sin if it involves harm or Hadd (leads to inflicting the Islamic corporal punishment on someone); as stated by the author of Az-Zawaajir, “The four hundred and forty major sin: Lying that involves a Hadd or harm. He extensively elaborated on this issue, and he mentioned the difference of opinions on the conditions for considering a lie as a major sin.”
With regard to backbiting, according to most scholars, it is one of the major sins.
Allah knows best.