Cold sales calls are, it seems, an occupational hazard of being the Head of IT in a mid-sized organisation. I've continued to take them because, just occasionally, serendipity dictates that the right supplier will happen to call on the right day. The hit rate is very low, though.
Most of the people doing the calling are friendly enough, and it is not a job that I'd like. But just a few (but sadly it is more than the useful ones) are rude, insulting, or just plain useless.
Some clues:
If I say that I don't need your product or service after you have explained why I might, please take the hint.
If you just regurgitate a list of key words that I spoke when you called before, please try to structure them into a sentence.
Please don't insult me by telling me you know my business better than I do.
mmitII 
Oh, the irony… on the day I write this I have not one, but two companies phoning to try and sell me Google Apps…