Default - These are preselected values. See the Race Relationships chart in Images to view what the default race settings are. There are also some locational differences. As the cosmopolitan capital, residents of Solitude express less racism than elsewhere in Skyrim. However, Nords who are residents of Windhelm or part of the Stormcloak faction express stronger racism. I've also built several exceptions into the default settings to reflect individual character traits present within the game. Also, your personal relationship with a merchant is more important than any general feelings they may have toward your race and will override any general racial bias.
Bartering does have its limitations. Many bigger (i.e., chain) businesses will not entertain the idea and even smaller organizations may limit the amount of goods or services for which they will barter (i.e., they may not agree to a 100% barter arrangement and instead require that you make at least partial payment). But in an economic crunch, bartering can be a great way to get the goods and services you need without having to pull money out of your pocket.
Barter is a contract wherein parties trade goods or commodities for other goods, as opposed to sale or exchange of goods for money. Barter is not applicable to contracts involving land, but solely to contracts relating to goods and services. For example, when a tenant exchanges the performance of various maintenance tasks around a house for free room and board, a barter has taken place.
Corporate barter focuses on larger transactions, which is different from a traditional, retail oriented barter exchange. Corporate barter exchanges typically use media and advertising as leverage for their larger transactions. It entails the use of a currency unit called a "trade-credit". The trade-credit must not only be known and guaranteed, but also be valued in an amount the media and advertising could have been purchased for had the "client" bought it themselves (contract to eliminate ambiguity and risk).
It is estimated that over 450,000 businesses in the United States were involved in barter exchange activities in 2010. There are approximately 400 commercial and corporate barter companies serving all parts of the world. There are many opportunities for entrepreneurs to start a barter exchange. Several major cities in the U.S. and Canada do not currently have a local barter exchange. There are two industry groups in the United States, the National Association of Trade Exchanges (NATE) and the International Reciprocal Trade Association (IRTA). Both offer training and promote high ethical standards among their members. Moreover, each has created its own currency through which its member barter companies can trade. NATE's currency is the known as the BANC and IRTA's currency is called Universal Currency (UC).