Answer: there should be none, a priori, as is considered ‘ideology’ what is resulting of ‘ideas’ or ‘intellectual insight’, which, in the understanding of many, should depend for its reliability on the inherent truth of logic and definition, leaving no place to affective expressions. In fact, nothing is less true, and most of ideologies are more some kind of attempt of rational presentation of severe affective disorders than rational exposures.
Why? Precisely, because most of them lack of rational foundation in logic and definition. If you are trying to mask some affective pretension through ideas, it can’t be but a severe disorder. To say: I may be angry with half the world for whatever reasons and say « I hate you all, bastards », giving an exact expression to my affective state, which may change, as affective. Now, if I build up a theory saying that « all those belonging to ‘alfa’ are this and the other and thus should be the general object of despise and hatred » I’m deviating my subjective affective state towards the pretension to a universal truth as depending on ideas. Thus, I’m neither able to assume my personal affective state, but, on top, I’m trying to convince the world of the fact they have to share my rejection towards others, for example. Which means that the person expressing this theory or ideology has a serious affective problem, which is very often the case.
A serious analysis of the logical structures of writings (Marx, for example, or even Freud) does allow the determination of the affective trouble hiding itself behind the pretension to science and reason.