It is something I am wondering, what can I tell when the PageRank of the domain is known, which is PR 1, yet there's no traffic analysis evident? In regards to potential traffic and similar, but also the value of the domain? If I would be about to buy a domain with a great page rank for example, would it mean that possible good ranking with good SEO, is far quicker to be achieved. Because that is something I would assume, yet is there more to it?
I think this is not only regarding the pagerank, it also about the alexa rank. Alexa is about traffic, Pagerank is about ranking on keywords.
you can analyze it by yourself with the SERPs, and estimated search volume for the keywords. and of course, Alexa. If serious buyer, you can always ask to insert your analytic into the site, and track it for 1-2 weeks. Sellers are pretty okay with this, especially for big deals.
for such situations, the most useful thing would be to track their traffic for sometime to understand the flow of people coming to the site, plus the kind of keywords they are ranking for