An important aspect of communicative convention of culture languages is style stratification of linguistic media against the background dichotomy standard - non-standard. The gradually declining level of speech culture in contemporary Czech shows that the loss of the ability and willingness of speakers to apply the standard variant of the language not only in writing but also in active speaking practice in a sufficiently wide range of speaking situations leads to the speakers' loss of the sensitivity to differentiate between linguistic layers and suitable variants of linguistic behaviour.
The paper summarizes the main causes of this condition.