It is easy to construct fallacious arguments by applying general statements to specific incidents that are obviously exceptions.
Generalizations that are weak generally have more exceptions (the number of exceptions to the generalization need not be a minority of cases) and vice versa.
This fallacy may occur when we confuse particulars ("some") for categorical statements ("always and everywhere"). It may be encouraged when no qualifying words like "some", "many", "rarely" etc. are used to mark the generalization.