After losing some deals that just seemed like there was no credible way we could lose, better "product", better price, better team, etc. You start asking hard questions about all the people involved and eventually someome will confidentially explain what happened. Especially people who actually need to work with the worse vendor that just got selected.

If you read through the settlement I linked ("The settlement also resolves allegations that ECW paid kickbacks to certain customers in exchange for promoting its product.") and other documentation regarding that case you can find details of several situations. I am singling out ECW there because that settlement exists. You would have to be pretty naive to think they were the only vendor engaged in that type of behavior and that the recipients of kick backs were only receiving kick backs from them alone.