There's a phrased in the sales world: “show up and throw up”.
It means that as a salesperson, if you don't take time to relate to your potential customer, to get to know them and their needs…
If you just jump right in and hit them with your cheesy, canned sales presentation right off the bat…
…it's like saying “hi” by throwing up on their shoes.
Gross analogy, I know. But apt, yes?
Jeff Sexton wrote a great little piece on how to avoid this phenomena at GrokDotCom (and that site should definitely go into your RSS reader).
Check out their post on web copy that makes you sick.