I agree with the general gist of 'treat me with respect, or you won't treat me at all'. Like eskie, I do my research before embarking on anything & usually drop a few clues to this effect, when first meeting. However, some 'professionals' seem to resent the idea of a customer being up to speed on things & get defensive or holier-than-thou - these are typically people that I can't do business with (unless no alternative exists). With medical types, I usually state my symptom & requirements, then let them do their diagnosis - if that diagnosis doesn't seem right, I'll explain why I think so & let them make their case to me. If I get any attitude from them, I'll stand my ground without getting argumentative & that doesn't work, then if at all possible, I'll go elsewhere.