An axiomatic basis for fuzzy rationality measures has already been int
roduced by the authors in a previous paper [5], formalizing the fact t
hat there exist degrees of consistency when preferences over a fixed s
et of alternatives are expressed in terms of fuzzy binary preference r
elations. This paper deals with some practical consequences. On the on
e hand, similarities and compositions of fuzzy rationality measures ar
e considered, showing natural ways of deriving new measures; on the ot
her, if basic stability properties are introduced in order to assure t
hat small intensity measurement errors never lead to big changes in th
e associate rationality value, it is shown that crisp (i.e., binary) r
ationality measures present serious difficulties when applied to fuzzy
preference relations.