One of my pet peeves is when a salesman barges unannounced into my office. They don't knock - they just waltz right in and start trying to sell me something. They look utterly dumbfounded when I ask them if they had an appointment; you can tell that the thought never even crossed their mind that perhaps I have a schedule, and it surely doesn't include talking to unwanted strangers who are more interested in meeting their monthly quotas than in helping my business.
It also irritates me when they don't seem to get the hint and can't take "no" for an answer. It appears that in their journeys they never picked up on two basic facts:
1 - People don't like being on the receiving end of cold calling.
2 - Cold-calling is highly ineffective (due in large part to #1, no doubt).
Memo to salesmen:
Why don't you try relationship marketing, or read a book a instead? I bet you'd see better results.