This study adopts the view that phraseological comparisons underlie constructional idioms, given that they can be considered partially lexically filled patterns, that is, form-meaning pairings endowed with a pragmatic meaning. Against this background, the [más feo que X] (‘very ugly’) construction is analyzed on the basis of the esTenTen18 corpus, which yields a total of 1,108 occurrences with the intensifying meaning. Under the assumption that Construction Grammar is a much more suitable approach for the study of semi-schematic constructions than traditional phraseology, this contribution aims to describe the five different senses that the construction can adopt, as well as to identify the conceptual fields of the slots that motivate its instances. Considering productivity and creativity as two sides of the same coin, the study determines whether Spanish speakers use more creative instances of the construction or lexicalized idioms, among which we focus on the highly entrenched [más feo que pegarle a un padre] micro-construction in order to analyze its productivity on the basis of its modifications and creative extensions attested in the corpus.