In modern video conferencing services, just as in common video delivery, most of the resource optimization is taken care of in the codec layer. Modern codecs like H.264 use detailed perceptual models to optimize the data reduction in way that it is least noticed by us. Already early evaluations of telecommunication systems could establish that there are different thresholds for a good quality depending on the situation. It is further known that subjective quality perceptions vary from user to user. But the space of user and context factors is still largely unexplored. To gain insight in which parameters are key in differentiating quality perception, we need to explore the interaction in different situations while keeping a tight control over the system parameters. In this paper we explore how clustering participants by their interaction or rating behavior can reveal subgroups that show significantly different perception of the QoE delivered by the same videoconferencing system. While for a cluster of users we find video quality to influence other QoE dimensions such as audio, for another cluster this is not the case. We explore whether this effect is due to conversational dynamics (contextual factor) or individual preferences (user factor) and discuss what this would mean for the design of future video-conferencing systems, that want to dynamically adapt to situation and participants.