Quite probably the company whose logo it was doesn't know that the pens are dodgy.

Indeed. The company making and printing the pens probably doesn't give a rats arse about how long the logo lasts in use or what kind of visibility is raised -- the company being promoted pays them, they supply pens, end of story. They probably don't expect anyone to provide "Your promotional pens are crap" feedback to the company being promoted which would scupper their chances of repeat business.