Culture clashes
Tourists are frequently disrespectful of local customs. Women (and men) often walk around in revealing clothing when the social norm is to politely cover yourself up. This is particularly important in places of worship and it is often considered extremely rude. This behavior can cause ill-will and can also cause the local people to stray from their beliefs and customs.
Ill will can also be caused by the way tourists interact with locals. Many take pictures of local people like animals in the zoo, without subtlety or permission, then move on without purchasing any of their crafts.