http://www.on4ww.be/OperatingPracticeEnglish.html
4. BE POLITE
This is the shortest but undoubtedly most important chapter in this document. At all times, be polite! Your transmitted signal is being heard by a lot of folks and agencies. You’ll go a long way by being polite, in our little ham world or in the outside world.
AD7MI: Sometimes in the rush and excitement of chasing DX it is easy to forget the other stations out there. The first part of our Amateur’s Code puts it well: Considerate… never knowingly operates in such a way as to lessen the pleasure of others.