I used to send crews to trade shows to man a booth. They had various forms and cards to be filled out by visitors. Pens disappeared almost as soon as they were put out. I think it was mostly a case of absent mindedness. My solution was to have them use stick pens, like the cheap bics, and put them out without the caps. People were less absent minded about putting a pen in their pocket or purse if it had no cap. It worked very well. I've recommended this to chashiers at the grocery store who have a similar problem losing pens when people sign credit card slips. They seem to like it, too.