When it comes to describing bad manners, there are several synonyms which can be used to convey the same message. For instance, the use of uncivilized, impolite, rude, discourteous, offensive or disrespectful can replace "bad manners". All of these words indicate behaviour that is improper and unacceptable within social norms. These words are generally used to criticize an individual's behaviour when they have acted in a disrespectful or discourteous manner towards others. It is important to use these words in context since they carry different nuances and connotations. In summary, whether you choose to use "bad manners" or its synonyms, the message will always be the same.