Clogging in porous media is a problem in environmental engineering, hydrogeology, soil science, and petrology. However, a comparison of the literature reveals qualitatively different clogging behavior in different porous media: in granular media filters, increasing clogging is associated with slower flow, more flocculated conditions, and smaller fractal dimensions. In soils and dead-end membranes, increasing clogging is associated with faster flow, more dispersed conditions, and larger fractal dimensions. This paper documents these differences, discusses them in light of two key intermediate variables, colloid accumulation and deposit morphology, then presents a new conceptual model that explains the reported clogging phenomena as a function of specific deposit, fractal dimension, and a new variable, deposit location. Testing this model is possible using recently introduced experimental techniques.