It's true that everyone enjoys a compliment now and then, but it's very easy to come across as manipulative and insincere when using a compliment as a way to strike up a conversation.

It is, in fact, manipulative -- the compliment was chosen as a way to get the person to engage in a conversation, and the assumption was made that the woman is vain enough to take the bait. I'd say it's doubly insulting more often than it's sincerely flattering.

There are occasionally exceptions when compliments are sincerely flattering to the recipient, but those are not usually times when the compliment is being used as the first step in a guy trying to get laid :) If they work, he'd already won her over in spite of the comment, not because of it.