The Market for Lemons cars, the dearth of formal credit markets in developing countries, and the difficulties that the elderly encounter in buying health insurance. However, not all players in a given market will follow the same rules or have the same aptitude of assessing quality. So there will always be a distinct advantage for some vendors to offer low-quality goods to the less-informed segment of a market that, on the whole, appears to be of reasonable quality and have reasonable guarantees of certainty. This is part of the basis for the idiom buyer beware. This is likely the basis for the idiom that
Beware of the dog a sign does not relieve the owner of responsibility for any harm which may come to people attacked by the dog. Beware of the dog Beware of the dog (also rendered as Beware of dog) is a warning sign indicating that a dangerous dog is within. Such signs may be placed to deter burglary even if there is no dog. Warning signs of this sort have been found in ancient Roman buildings such as the House of the Tragic Poet in Pompeii, which contains a mosaic with the caption "cave canem" (). Some suppose that these warnings may sometimes have