In general, people do not pay much attention to the behaviour of others, unless it is dramatically different from the norm. A person can continue doing something marginally odd for a long time, without attracting attention. However, once people notice the oddity, they tend to over-react. This phenomenon occurs with eating habits, cleanliness or personal mannerisms. People either do not notice anything odd, or, if they do, they place the individual concerned into a category of deviant behaviour which probably exaggerates the situation considerably: ‘Felicity drinks like a fish’; ‘Marcia's house is like a pigsty’; ‘Cuthbert's continually scratching himself’.

The same thing happens with language. People either do not notice a minor deviation from the norm, or they over-react to it, and make comments such as ‘Egbert always drops his aitches’, even though Egbert may only drop a few of them. Consider the case of words which end in t in British English, such as what, hot. A very large number of people alter t to a glottal stop when it occurs before another word, as in wha(t) stupidity, ho(t) water bottle, but they usually do not realize they are doing so, nor do they notice other people doing so.