Everyone agrees that if a site doesn't rank in the top 10 or 20 when doing a travel coupon search you may not see it. This is why your search should be very specific as to the exact travel coupon phrase you are looking for. If this is a brand name the list the travel coupon brand.
If the creator of the page tries to stuff travel coupon in more than is needed then the page may not obtain a good ranking and you may never see it. Webmasters should only use those travel coupon and like phrases that are also used in the copy of the page and is the true subject of the web page.