Tales & Trails of a Traveling Wiseguy

Just out of curiosity, how do you tell the difference between someone who collects lots of info from different suppliers and then eventually comes back and buys for reasons, versus people who are just poking around? I mean, some people probably even think they want to do something/buy something and then as they collect info either decide that info has made it not the right thing, or even something may have changed?

Like, I'm sure there are people who are always collecting info, never buying. But how do you tell?