Folk linguistics

Folk linguistics consists of statements, beliefs, or practices concerning language which are based on uninformed speculation rather than the scientific method. Folk linguistics sometimes arises when scientific conclusions about language come off as counterintuitive to native speakers. However, folk linguistics is also often motivated by ideology and nationalism.
Examples.
Jackendoff (2003) cites the following statements as typical examples of folk-linguistic beliefs.
Other beliefs may include:
Notes.
a. Ray Jackendoff, 
b. Linguistic Purism in Germany - Folk Linguistics via the Internet Archive