There's a store near my house that has a "one day only sale" every week. So when you go and see something, you're always like, "eh, it'll be on sale at the end of the week, why buy it now."
I used to get all excited when I got the VS email about a fare sale, but now I know if I wait, there will be another, so why buy a ticket now.
I certainly agree with ChuckC's point though. At DL, we're always advertising something, usually through a big vinyl banner behind the ticket counters, that changes every month or so. You get all sorts of people checking it out, from cab drivers, to US Airways Chairman's Preferred customers. Now if that Chairman's Preferred customer tries it once, do we have a chance at getting a regular customer? Absolutely.
Hense the other reason why I always make announcements like, "Delta Connection is pleased to announce the early arrival of flight xxxx with service from yyyyyyy", while the US Air customers are deplaning off their regular 2 hour delayed arrival.
One of my co-workers even adds, "All deplaning customers may be met momentarily as they claim their luggage at baggage claim.", of course we only add that when US Air is announcing that their flight came in with NO BAGS onboard, and everyone needs to go to the counter to file a claim. [8D]