I have been asked how (and why) researchers categorise visitors. Well, here's some of the ways they do that (and a little speculation as to why they do that)!
Here's some ways visitors have been categorised as reported in George Hein's 1998 book Learning in the Museum (London: Routledge):
Wolf & Tymitz (1978)
Bicknell & Mann (1993)
Veron & Lavasseur (1989)
I always remember George MacDonald (formerly of the CMA and Museum Victoria) who called visitors 'streakers, strollers and students' which I quite like as it explains different visiting patterns really well I think.
John Falk, in his 2006 Curator article An Identity-Centred Approach to Understanding Museum Learning (pp151-166), classified visitors as:
Visit because of curiosity and/or general interest in discovering more about content area of institution
Described themselves as curious people
Satisfying needs and desires of someone they cared about (other than themselves)
Strong knowledge and interest in content areas
Specific agendas for visit
Collect an experience to say they’ve 'been there done that'
Visit to reflect, rejuvenate, just ‘bask in the wonder of the place’
In my own thesis The Interrelationships Between Adult Museum Visitors' Learning Identities and their Museum Experiences, I found that there were three roles played by visitors during a visit: the 'visit manager' by directing and organising; the 'museum expert' in explaining, clarifying and correcting; and the 'learning-facilitator' through questioning, linking, reminiscing and wondering. These roles were interchangeable, occurred simultaneously and were dependent on both the social context of the visit and the group composition, particularly the ages of any accompanying children.
So, my view is that we like categorising visitors because it makes our lives easier and also that is the nature of museum work - to classify and explain. However, we need to remember that these are only an indication of the nature of visitors and that human nature is ever-changing and ever-fluid (and often inexplicable).