"Sell" is a common expression of the principle of harming the integrity, morality, authenticity of others or in exchange for personal gains such as money. In music or art, selling out is related to attempts to tailor materials for mainstream or commercial audiences. For example, musicians who change their materials to cover a wider audience and thus generate more revenue may be tagged by fans who have previously noted "sales volume.". Selling out also means giving up or ignoring someone's actions, so the term "selling" (someone or something) means something else or someone else. Depending on the context, the term can also be used as "sold out.".

In a political movement, "surplus" refers to an individual or group that adheres to an ideology and only takes the opposite action after following up these claims, for example, a revolutionary group claims to fight for a specific reason, but fails to continue to do so after winning.

One example of political "selling out" is the alliance of one party with another that has historically opposed, such as Nick Clegg, leader of the LDP, with the conservatives after the 2010 British election. He broke his promise against increasing students' tuition.

After changing the direction of art, artists may also be accused of "selling out". This conclusion is usually because people think that the reason why artists change their artistic style or direction is only the potential material benefits. This ignores other reasons for the development of art, which may lead artists to move in a new direction from the perspective of attracting their original fans. The improvement of artist's music level or the change of taste may also be the cause of this change.

At other times, artists, including those with political leanings, have expressed dissatisfaction with the term, arguing that people's desire for material benefits is simply the result of the band's quest to expand its message. For such artists, no matter whether they make any actual artistic changes or not, they should not become the mainstream or sign a larger label to avoid "selling", so as to prevent them from targeting a wider audience, and arbitrarily hinder the mainstream success of artists. Therefore, this accusation assumes that the mainstream success must run counter to the original intention of artists. For example, when asked if he wanted to sign a major record company, rage against the machine replied, "we are not interested in preaching the adherents. It's great to be an anarchist abstainer, but it's also great to have access to people with revolutionary information, from Granada heights to Stuttgart.